JPWO2019030981A1 - Radio access network node, core network node, and radio terminal and methods thereof - Google Patents

Abstract

The master RAN node (1) sends in the core network (4) a request to modify the first PDU session already established between the wireless terminal (3) and the user plane function (6) in the core network (4). Sent to the control plane function (5). The modification request implicitly or explicitly indicates that a PDU session split is required for the first PDU session. The modification request is for a specific one or more QoS flows of the plurality of QoS flows associated with the first PDU session to be the first between the user plane function (6) and the master RAN node (1). Causes the control plane function (5) to control the user plane function (6) to move from the second tunnel between the user plane function (6) and the secondary RAN node (2). This contributes, for example, to the implementation of PDU session splits in wireless communication networks.

Description

TECHNICAL FIELD The present disclosure relates to a wireless communication system, and more particularly, to a dual-connectivity operation in which wireless terminals simultaneously use a plurality of cells operated by different wireless access network nodes.

The 3rd Generation Partnership Project (3GPP) is working on the standardization of the 5th generation mobile communication system (5G) for introduction after 2020. 5G is a combination of continuous improvement and evolution (enhancement/evolution) of LTE and LTE-Advanced and innovative improvement and development by introducing a new 5G air interface (new Radio Access Technology (RAT)). It is supposed to be done. The new RAT is, for example, a frequency band higher than the frequency band (eg, 6 GHz or less) targeted for continuous development of LTE/LTE-Advanced, for example, a centimeter wave band of 10 GHz or more and a millimeter wave band of 30 GHz or more. Support wave bands.

In this specification, the fifth-generation mobile communication system is also referred to as a 5G System or a Next Generation (NextGen) System (NG System). The new RAT for 5G System is called New Radio (NR), 5G RAT, or NG RAT. The new Radio Access Network (RAN) for 5G System is called 5G-RAN or NextGen RAN (NG RAN). The new base station in 5G-RAN is called NR NodeB (NR NB) or gNodeB (gNB). The new core network for 5G System is called 5G Core Network (5G-CN or 5GC) or NextGen Core (NG Core). A wireless terminal (User Equipment (UE)) connected to the 5G System is called a 5G UE, a NextGen UE (NG UE), or simply a UE. Formal names such as RAT, UE, radio access network, core network, network entities (nodes), and protocol layers for 5G System will be determined in the future as standardization work progresses.

The term “LTE” used in the present specification includes improvements and developments of LTE and LTE-Advanced to enable interworking with 5G System, unless otherwise specified. Improvements and developments in LTE and LTE-Advanced for interworking with 5G Systems are also called LTE-Advanced Pro, LTE+, or enhanced LTE (eLTE). Further, as used herein, "Evolved Packet Core (EPC)", "Mobility Management Entity (MME)", "Serving Gateway (S-GW)", and "Packet Data Network (PDN) Gateway (P-GW). )” and other terms relating to LTE networks or logical entities include these improvements and developments to enable interworking with 5G Systems unless otherwise noted. The improved EPC, MME, S-GW, and P-GW are, for example, enhanced EPC (eEPC), enhanced MME (eMME), enhanced S-GW (eS-GW), and enhanced P-GW (eP-GW). ) Is also called.

In LTE and LTE-Advanced, for quality of service (QoS) and packet routing, bearers for each QoS class and for each PDN connection are RAN (ie, Evolved Universal Terrestrial RAN (E-UTRAN)) and core network (ie, EPC) used both. That is, in the Bearer-based QoS (or per-bearer QoS) concept, one or more Evolved Packet System (EPS) bearers are set between the UE and the P-GW in the EPC, and a plurality of Evolved Packet System (EPS) bearers having the same QoS class are set. Service Data Flows (SDFs) are transferred through one EPS bearer that satisfies these QoS. SDF is one or more packet flows that match SDF templates (i.e., packet filters) based on Policy and Charging Control (PCC) rules. Also, for packet routing, each packet sent through the EPS bearer identifies which bearer (ie, General Packet Radio Service (GPRS) Tunneling Protocol (GTP) tunnel) the packet is associated with. ) For information. Also, the QoS Class Identifier (QCI) is used as the information of the QoS class. The 3GPP specification defines the relationship between each QCI and its associated QoS characteristics (eg, packet and transmission delay requirements (i.e., Packet Delay Budget)).

On the other hand, in 5G System, although radio bearers may be used in NG-RAN, it is considered that bearers are not used in the 5GC and at the interface between 5GC and NG-RAN. Specifically, PDU flows are defined instead of EPS bearer, and one or more SDFs are mapped to one or more PDU flows. The PDU flow between the 5G UE and the user plane termination entity in NG Core (i.e., the entity corresponding to the P-GW in EPC) corresponds to the EPS bearer in the EPS Bearer-based QoS concept. PDU flow corresponds to the finest granularity of packet forwarding and treatment within a 5G system. That is, the 5G system adopts the Flow-based QoS (or per-flow QoS) concept instead of the Bearer-based QoS concept. In the Flow-based QoS concept, QoS is handled on a PDU flow basis. In the 5G system QoS framework, the PDU flow is specified by the PDU flow ID in the header encapsulating the Service Data Unit of the tunnel of the N3 interface. The N3 interface is a user plane interface between the 5GC and gNB (i.e., NG-RAN). The association between the 5G UE and the data network is called a PDU session. The PDU session is a term corresponding to PDN connection (PDN connection) of LTE and LTE-Advanced. Multiple PDU flows can be configured within one PDU session. The 3GPP specifications define 5G QoS Indicator (5QI) corresponding to LTE QCI for 5G System.

The PDU flow is also called "QoS flow". The QoS flow is the finest granularity of QoS treatment within a 5G system. User plane traffic with the same N3 marking value in the PDU session corresponds to the QoS flow. The N3 marking corresponds to the above-mentioned PDU flow ID and is also called QoS flow Identity (QFI) and also Flow Identification Indicator (FII). Here, there is a one-to-one relationship between each 5QI specified in the specification and the corresponding QFI having the same value (number) as this (i.e., one-to-one mapping).

Figure 1 shows the basic architecture of a 5G system. The UE establishes one or more Signaling Radio Bearers (SRBs) and one or more Data Radio Bearers (DRBs) with the gNB. 5GC and gNB establish the control plane interface and the user plane interface for the UE. The control plane interface between 5GC and gNB (ie, RAN) is called N2 interface, NG2 interface, or NG-c interface, which transfers Non-Access Stratum (NAS) information and controls between 5GC and gNB. Used for information (eg, N2 AP Information Element). The user plane interface between the 5GC and the gNB (ie, RAN) is called N3 interface, NG3 interface, or NG-u interface, and the packets of one or more PDU flows in the PDU session of the UE. Used to transfer.

It should be noted that the architecture shown in FIG. 1 is only one of multiple 5G architecture options (or deployment scenarios). The architecture shown in FIG. 1 is called "Standalone NR (in NextGen System)" or "Option 2". 3GPP is further exploring some network architectures for multi-connectivity operation using E-UTRA and NR radio access technologies. A typical example of multi-connection operation is a dual connection (Dual Connectivity (DC) in which one master node (Master node (MN)) and one secondary node (Secondary node (SN)) cooperate with each other to communicate with one UE at the same time. )). Dual connection operation using E-UTRA and NR radio access technologies is called Multi-RAT Dual Connectivity (MR-DC). MR-DC is a dual connectivity between an E-UTRA node and an NR node (E-UTRA and NR nodes).

In MR-DC, one of E-UTRA node (ie, eNB) and NR node (ie, gNB) operates as a master node (Master node (MN)), and the other operates as a secondary node (Secondary node (SN)). , And at least the MN is connected to the core network. The MN provides the UE with one or more Master Cell Group (MCG) cells, and the SN provides the UE with one or more Secondary Cell Group (SCG) cells. MR-DC includes “MR-DC with the EPC” and “MR-DC with the 5GC”.

MR-DC with the EPC includes E-UTRA-NR Dual Connectivity (EN-DC). In EN-DC, the UE is connected to the eNB that operates as the MN and the gNB that operates as the SN. Furthermore, eNB (i.e., Master eNB) is connected to EPC, gNB (i.e. Secondary gNB) is connected to Master eNB via X2 interface.

MR-DC with the 5GC includes NR-E-UTRA Dual Connectivity (NE-DC) and NG-RAN E-UTRA-NR Dual Connectivity (NG-EN-DC). In NE-DC, UE is connected to gNB operating as MN and eNB operating as SN, gNB (ie, Master gNB) is connected to 5GC, eNB (ie Secondary eNB) is Master gNB via Xn interface. Connected. On the other hand, in NG-EN-DC, UE is connected to eNB operating as MN and gNB operating as SN, eNB (ie, Master eNB) is connected to 5GC, gNB (ie Secondary gNB) is via Xn interface. Connected to the Master eNB.

2, 3 and 4 respectively show network configurations of the three DC types mentioned above, namely EN-DC, NE-DC and NG-EN-DC. In addition, the 5G System supports dual connectivity between two gNBs. Dual connectivity between two gNBs is referred to herein as NR-NR DC. FIG. 5 shows a network configuration of NR-NR DC.

FIG. 6 shows SRBs and DRBs supported by the above-mentioned three MR-DC types and NR-NR DC. Note that FIG. 6 illustrates bearer types supported in 3GPP Release 15 currently under discussion in 3GPP. Therefore, the bearer types supported by these DC types may be different than in FIG.

The MCG SRB is an SRB established between the UE and the MN in the MCG cell, and Radio Resource Control Protocol Data Units (RRC PDUs) generated by the MN can be transported by the MCG SRB. The RRC PDUs generated by the SN can be transported to the UE via the MN and the MCG SRB. Instead, the SN establishes an SRB (SCG SRB) between the UE and the SN in the SCG cell to directly transport the RRC PDUs generated by the SN between the UE and the SN. be able to. The SCG SRB is called SRB3, for example. MCG split SRB provides duplication of RRC PPUs that can be transported via MCG SRB, allowing the same RRC PDUs to be transported in both MCG and SCG cells.

The MCG bearer is a user plane bearer whose radio protocol is placed only in the MCG. The MCG split bearer is a user plane bearer whose radio protocol is split in the MN and belongs to both MCG and SCG. The SCG bearer is a user plane bearer whose radio protocol is placed only in the SCG. The SCG split bearer is a user plane bearer whose radio protocol is split at the SN and belongs to both SCG and MCG. The MCG split bearer and SCG split bearer perform duplication of PDCP data PDUs and allow the same PDCP data PDUs to be transported in both MCG cells and SCG cells.

The layer 2 function of NR (i.e., gNB and UE) is not the same as the layer 2 function of LTE (i.e., eNB and UE). For example, the layer 2 of the NR includes four sublayers of a Service Data Adaptation Protocol (SDAP) sublayer, a Packet Data Convergence Protocol (PDCP) sublayer, a Radio Link Control (RLC) sublayer, and a Medium Access Control (MAC) sublayer. In the NR PDCP sublayer, the PDCP Sequence Number (SN) size for DRBs is 12 bits or 18 bits, which is the LTE PDCP SN size (ie, 7 bits, 12 bits, 15 bits, or 18 bits). It is a subset. However, when LTE eNB is connected to 5GC, the layer 2 of LTE (i.e., eNB and UE) contains a SDAP sublayer. On the other hand, when NR gNB is operated as SN in EN-DC, layer 2 of NR (i.e., gNB and UE) does not have to implement the SDAP sublayer. Alternatively, if NR gNB is operated as SN in EN-DC, layer 2 of NR (ie, gNB and UE) is implemented such that the SDAP sublayer is transparent to PDUs passing through it. May be. That is, Transparent Mode may be implemented in the SDAP sublayer.

The main services and functions of the SDAP sublayer include mapping between QoS flows and data radio bearers (DRB), and marking of QoS flow identities (QFI) on downlink (DL) and uplink (UL) packets. A single protocol entity of SDAP is configured for each individual PDU session (except DC). For DC, two entities can be configured (i.e., one for MCG and another for SCG).

FIG. 7 illustrates the 5GC non-DC QoS architecture described above (see Non-Patent Document 1). For each UE, the 5GC establishes one or more PDU sessions. For each UE, the NG-RAN establishes one or more DRBs per PDU session. NG-RAN maps packets belonging to different PDU sessions to different DRBs. In other words, the NG-RAN does not map QoS flows (i.e., packets transmitted in the QoS flows) belonging to different PDU sessions to the same DRB. Therefore, the NG-RAN establishes at least one default DRB for each PDU session indicated by the 5GC in the PDU Session establishment. In the case of non-DC, packets (packets) of multiple QoS flows belonging to one PDU session are between the NG-RAN node (ie, gNB) and the user plane function (UPF) within 5GC. It will be delivered through the NG-U tunnel to be set up. The NG-U tunnel is, for example, a General Packet Radio Service (GPRS) Tunneling Protocol (GTP) tunnel. The end node in the 5GC of the NG-U tunnel is also called the user plane gateway (UPGW). In the 5GC QoS concept, 5GC allows a plurality of QoS flows having different QoS levels within one PDU session to be transferred through one NG-U tunnel. The NG-U tunnel is also called an N3 tunnel, an NG3 tunnel, a PDU tunnel, or a PDU session tunnel.

Non-Patent Documents 2, 3 and 4 give an option to split NG-U resources for one PDU session in UPF (UPGW) in 5GC when DC is executed in NG-RAN. is suggesting. DC here includes NR-NR DC and MR-DC with the 5GC (e.g.., NE-DC and NG-EN DC). Specifically, DC in a 5G system requires that two NG-U tunnels be simultaneously supported for one PDU session. One NG-U tunnel is set up between UPF (UPGW) and master node (Master Node (MN)), and the other NG-U tunnel is between UPF (UPGW) and secondary node (Secondary Node (SN)). Set in between. In this specification, such a configuration is referred to as a PDU session split. That is, PDU session split can be defined as a configuration in which two or more NG-U tunnels are simultaneously supported for one PDU session. In other words, the PDU session split can be defined as a configuration that allows a part of one PDU session to be sent to the MN and the rest to be sent to the SN(s).

In PDU session split, which is being considered in 3GPP, the MN transfers some of a plurality of QoS flows of one PDU session transferred via the MN to the SN. FIG. 8 shows the movement of the QoS flow disclosed in Non-Patent Documents 3 and 4 from the MN to the SN. In the example of FIG. 8, the QoS flow 802 of the two QoS flows 801 and 802 of one PDU session transferred via the MN is moved to the SN. The QoS flow 802 transferred from the MN to the SN is transferred via the NG-U tunnel 822 set between the UPF (UPGW) and the SN. That is, in the DC in the 5G system, different QoS flows 801 and 802 of one PDU session need to be simultaneously sent to the MN and the SN via two different NG-U tunnels 821 and 822. The QoS flow 801 sent to the MN may be called an MCG flow, and the QoS flow 802 sent to the SN may be called an SCG flow.

3GPP TS 38.300 V0.4.1 (2017-06), “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NR; NR and NG-RAN Overall Description; Stage 2 (Release 15)”, June 2017 3GPP Tdoc R2-1703252, Samsung, “NR + NR DC: QOS Architecture”, 3GPP TSG-RAN WG2 Meeting #97 bis, April 2017 3GPP Tdoc R3-171711, Ericsson, “PDU Session Split at UPF”, 3GPP TSG-RAN WG3 Meeting #96, May 2017 3GPP Tdoc R3-171898, NTT DOCOMO, INC., “Response to R3-171711 (PDU Session split at UPF)”, 3GPP TSG-RAN WG3 Meeting #96, May 2017

Non-Patent Documents 2, 3 and 4 disclose that signaling or coordination between a MN (eg, MgNB) and a core network (eg, 5GC) is required for PDU session split. ing. Further, Non-Patent Documents 2, 3 and 4 disclose that signaling or coordination between MN (eg, MgNB) and SN (eg, SgNB) is required for PDU session split. ing. However, Non-Patent Documents 2, 3, and 4 do not disclose the details of signaling for PDU session split. Therefore, it is not clear how to perform PDU session split.

One of the aims of the embodiments disclosed herein is to provide an apparatus, method, and program that contribute to the implementation of PDU session splits in a wireless communication network. It should be noted that this goal is only one of the goals that the embodiments disclosed herein seek to achieve. Other objects or problems and novel features will become apparent from the description of the present specification or the accompanying drawings.

In a first aspect, a master radio access network (RAN) node includes a memory and at least one processor coupled to the memory. The at least one processor is configured to send a modification request of a first PDU session already established between the wireless terminal and a user plane function in the core network to a control plane function in the core network. The modification request implicitly or explicitly indicates that a PDU session split is required for the already established first PDU session. The modification request is for the user plane function and the master RAN node to specify one or more specific QoS flows among a plurality of Quality of Service (QoS) flows associated with the already established first PDU session. Causes the control plane function to control the user plane function to move from a first tunnel between the user plane function and a second tunnel between the user plane function and a secondary RAN node.

In a second aspect, the control plane node located in the core network includes a memory and at least one processor coupled to the memory. The at least one processor is configured to receive a modification request of a first PDU session already established between a wireless terminal and a user plane function in the core network from a master radio access network (RAN) node. .. The modification request implicitly or explicitly indicates that a PDU session split is required for the already established first PDU session. The at least one processor is further responsive to receipt of the modification request to identify one or more of a plurality of Quality of Service (QoS) flows associated with the already established first PDU session. Controlling the user plane function to move a QoS flow of the same from a first tunnel between the user plane function and the master RAN node to a second tunnel between the user plane function and a secondary RAN node. Composed.

In a third aspect, a Secondary Radio Access Network (RAN) node includes a memory and at least one processor coupled to the memory. The at least one processor is configured to receive an inter-node message requesting allocation of resources for dual connectivity for a wireless terminal from a master RAN node. The inter-node message further implicitly or explicitly indicates that the PDU session split is applied to the already established first PDU session between the wireless terminal and the user plane function in the core network. .. In the PDU session split, one or more first QoS flows of a plurality of Quality of Service (QoS) flows associated with the first PDU session are defined by the user plane function and the master RAN node. Via a first tunnel between the one or more second QoS flows of the plurality of QoS flows and a second tunnel between the user plane function and the secondary RAN node. Contains the configuration to be transferred.

In a fourth aspect, a wireless terminal includes a memory and at least one processor coupled to the memory. The at least one processor is configured to receive an RRC connection reconfiguration message indicating a secondary cell group configuration for dual connectivity from a master (RAN) node or a secondary RAN node. The RRC connection reconfiguration message further implicitly or explicitly indicates that PDU session split is applied to the already established first PDU session between the wireless terminal and a user plane function in the core network. Shown in. In the PDU session split, one or more first QoS flows of a plurality of Quality of Service (QoS) flows associated with the first PDU session are defined by the user plane function and the master RAN node. And a second QoS flow of one or more of the plurality of QoS flows is transferred via a second tunnel between the user plane function and a secondary RAN node. Including the configuration.

In a fifth aspect, a method in a master radio access network (RAN) node controls a request in a core network to modify an already established first PDU session between a wireless terminal and a user plane function in the core network. Includes sending to plain function. The modification request implicitly or explicitly indicates that a PDU session split is required for the already established first PDU session.

In a sixth aspect, a method in a control plane node located in a core network provides a master radio request for modification of an already established first PDU session between a wireless terminal and a user plane function in the core network. Including receiving from an access network (RAN) node. The modification request implicitly or explicitly indicates that a PDU session split is required for the already established first PDU session. In addition, the method may include selecting one or more specific QoS flows of the plurality of Quality of Service (QoS) flows associated with the already established first PDU session from the user plane function and the master RAN. Controlling the user plane function to move from a first tunnel between the nodes to a second tunnel between the user plane function and a secondary RAN node.

In a seventh aspect, a method in a secondary radio access network (RAN) node comprises receiving an internode message requesting to allocate resources for dual connectivity for a wireless terminal from a master RAN node. The inter-node message further implicitly or explicitly indicates that the PDU session split applies to the already established first PDU session between the wireless terminal and the user plane function in the core network. ..

In an eighth aspect, a method in a wireless terminal includes receiving an RRC connection reconfiguration message indicating a secondary cell group setting for dual connectivity from a master (RAN) node or a secondary RAN node. The RRC connection reconfiguration message further implicitly or explicitly indicates that PDU session split is applied to the already established first PDU session between the wireless terminal and a user plane function in the core network. Shown in.

In a ninth aspect, the program, when read by a computer, includes a group of instructions (software code) for causing the computer to perform the method according to the fifth, sixth, seventh, or eighth aspect described above. Including.

According to the above aspect, it is possible to provide an apparatus, a method, and a program that contribute to implementation of PDU session split in a wireless communication network.

It is a figure which shows the basic architecture of 5G System. It is a figure which shows the network structure of EN-DC. It is a figure which shows the network structure of NE-DC. It is a figure which shows the network structure of NG-EN-DC. It is a figure which shows the network structure of NR-NR DC. 3 is a table showing bearer types supported by the three DC types under discussion in 3GPP. It is a figure which shows the non-DC QoS architecture of 5G System. It is a figure which shows NR-NR DC QoS architecture of 5G System. It is a figure which shows the structural example of the wireless communication network which concerns on some embodiment. 5 is a flowchart showing an example of operation of the master node according to the first embodiment. It is a flow chart which shows an example of operation of a control plane functional entity concerning a 1st embodiment. It is a sequence diagram which shows an example of the signaling regarding the PDU session split which concerns on 1st Embodiment. It is a figure which shows an example of a format of a "PDU Session Request To Be Modified List" information element (Information Element (IE)). It is a figure which shows an example of a format of "PDU Session Request To Be Modified List" IE. It is a figure which shows an example of a format of "PDU Session Request To Be Modified List" IE. It is a sequence diagram which shows an example of the signaling regarding the PDU session split which concerns on 1st Embodiment. It is a figure which shows an example of a format of "PDU Session Request To Be Setup List" IE. It is a flowchart which shows an example of operation|movement of the control plane functional entity which concerns on 2nd Embodiment. It is a sequence diagram which shows an example of the signaling regarding the PDU session split which concerns on 2nd Embodiment. It is a flowchart which shows an example of operation|movement of the control plane functional entity which concerns on 4th Embodiment. It is a sequence diagram which shows an example of the signaling regarding the PDU session split which concerns on 4th Embodiment. It is a flowchart which shows an example of operation|movement of the master node which concerns on 5th Embodiment. It is a sequence diagram which shows an example of the signaling regarding the PDU session split which concerns on 5th Embodiment. It is a flowchart which shows an example of operation|movement of the master node which concerns on 7th Embodiment. It is a sequence diagram which shows an example of the signaling regarding the PDU session split which concerns on 7th Embodiment. It is a sequence diagram which shows an example of operation|movement of the wireless terminal which concerns on 7th Embodiment. It is a sequence diagram which shows an example of the signaling regarding the PDU session split which concerns on 8th Embodiment. It is a sequence diagram which shows an example of the signaling regarding the PDU session split which concerns on 8th Embodiment. It is a block diagram which shows the structural example of the master node which concerns on some embodiment. It is a block diagram which shows the structural example of the wireless terminal which concerns on some embodiment. It is a block diagram showing the example of composition of the control plane functional entity concerning some embodiments.

Hereinafter, specific embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numerals, and for the sake of clarity of explanation, duplicated description will be omitted as necessary.

The plurality of embodiments described below may be implemented independently or may be implemented in combination as appropriate. The plurality of embodiments have novel features different from each other. Therefore, these plurality of embodiments contribute to solving different purposes or problems, and contribute to achieving different effects.

The embodiments shown below are mainly described for NR-NR DC and MR-DC with the 5GC. However, these embodiments may be applied to other wireless communication systems that support DC architectures using other RATs.

<First Embodiment>
FIG. 9 shows a configuration example of a wireless communication network according to some embodiments including this embodiment. In the example of FIG. 9, the wireless communication network includes a master node (MN) 1, a secondary node (SN) 2, a UE 3, and a core network 4. The wireless communication network shown in FIG. 9 supports NR-NR DC or MR-DC with the 5GC. That is, each of MN1 and SN2 is an NR node (ie, gNB) or an E-UTRA node (ie, eNB). The MN1 and SN2 are connected to the core network 4 via the interfaces 901 and 904. The core network 4 is 5GC. The interfaces 901 and 904 are NG interfaces (ie, NG-c and NG-u, NG2 and NG3, or N2 and N3). An interface 903 connects between MN1 and SN2. The interface 903 is an Xn interface.

The core network 4 includes a control plane function (CPF) and a user plane function (UPF). The control plane functions include, for example, Access and Mobility Management Function (AMF), Session Management Function (SMF), and Policy Control function (PCF). Control plane functionality is provided by one or more control plane functional entities (or one or more control plane nodes). User plane functionality is provided by one or more user plane functionality entities (or one or more user plane nodes). The example of FIG. 9 shows one AMF/SMF entity 5 and one UPF entity 6. The AMF/SMF entity 5 provides AMF or SMF or both. The AMF/SMF entity 5 may include, for example, one or more entities, one or more physical nodes, or one or more computers. Similarly, UPF entity 6 may also include one or more entities, one or more physical nodes, or one or more computers. For example, the UPF entity 6 may be provided for each PDU session, or multiple UPF entities 6 may be used for one PDU session.

UE3 supports NR-NR DC or MR-DC with the 5GC or both. That is, the UE 3 supports a dual-connectivity operation using the NR radio access technology or the E-UTRA and the NR radio access technology. UE3 has the ability to communicate simultaneously with MN1 and SN2. In other words, UE3 has the ability to aggregate cells belonging to the master cell group (Master Cell Group (MCG)) provided by MN1 with cells belonging to the secondary cell group (Secondary Cell Group (SCG)) provided by SN2. Have. The MCG contains one or more cells provided using the Master RAT. The SCG includes one or more cells provided using the secondary RAT. The air interface 902 between the MN1 and the UE3 provides a control plane connection (e.g., RRC connection, signaling radio bearers (SRBs)) and a user plane connection (e.g., data radio bearers (DRBs)). On the other hand, the air interface 905 between the SN2 and the UE3 includes at least a user plane connection. The air interface 905 may or may not include a control plane connection.

MN1, SN2, UE3 and core network 4 are configured to support PDU session splits. In the following, the operations for PDU session split performed by these nodes or entities are described.

FIG. 10 is a flowchart showing an example of the operation of the MN 1. In step 1001, the MN 1 sends a request to modify the already established PDU session to the core network 4. The modification request implicitly or explicitly indicates that a PDU session split is required for an already established PDU session for UE3. In step 1002, the MN 1 receives the response message to the modification request from the core network 4.

FIG. 11 is a flowchart showing an example of the operation of the core network 4. The procedure of FIG. 11 is performed by the AMF/SMF entity 5. In step 1101, the AMF/SMF entity 5 receives from the MN 1 a request for modifying an already established PDU session (which implicitly or explicitly indicates the necessity of PDU session split).

The AMF/SMF entity 5 analyzes the received modification request and determines whether it is necessary to perform PDU session split (or whether PDU session split is requested). That is, if the modification request indicates that PDU session splitting is required, the AMF/SMF entity 5 has two or more RAN nodes (eg, MN1 and SN2) that have already established PDU sessions for UE3. ) Needs to be split.

When PDU session splitting is required, the AMF/SMF entity 5 sends one or more specific QoS flows among the plurality of QoS flows associated with the already established PDU session to the MN-1. The UPF entity 6 is controlled to move from the U tunnel to the NG-U tunnel from SN2 (step 1102). In some implementations, the AMF/SMF entity 5 duplicates the same PDU session ID for these two tunnels to set up an NG-U tunnel to MN1 and an NG-U tunnel to SN2 ( That is, reuse the same PDU session ID). When the AMF/SMF entity 5 cannot apply the split to the PDU session in which the PDU session split is required (or the PDU session split is requested), the AMF/SMF entity 5 returns a response message indicating that to the MN 1. Good.

In some implementations, a PDU SESSION RESOURCE MODIFY INDICATION message may be used to send the modification request shown in step 1001 (and step 1101). This PDU SESSION RESOURCE MODIFY INDICATION message is used by MN1 to request modification of an established PDU session (session(s)) for a particular UE. The PDU SESSION RESOURCE MODIFY INDICATION message is one of the NG Application Protocol (NGAP) (or N2 Application Protocol (N2AP)) messages sent via the NG-c (or N2) interface.

FIG. 12 shows an example in which the PDU SESSION RESOURCE MODIFY INDICATION message is used. In step 1201, the MN 1 sends a PDU SESSION RESOURCE MODIFY INDICATION message including a PDU session split request to the AMF/SMF entity 5. In step 1202, the AMF/SMF entity 5 sends a PDU SESSION RESOURCE MODIFY CONFIRM message to the MN 1. This PDU SESSION RESOURCE MODIFY CONFIRM message corresponds to the response message shown in step 1002 (and step 1103).

In one example, the modification request in the PDU SESSION RESOURCE MODIFY INDICATION message may be PDU session type information that explicitly indicates the need for PDU session splits. The AMF/SMF entity 5 has two or more RAN nodes (eg, MN1 and SN2) if the PDU session type information indicates that PDU session split is required (or required). You may recognize that you need to be split into. Conversely, if the PDU session type information does not indicate that PDU session split is required (or required), the AMF/SMF entity 5 determines that the PDU session is in another RAN node (eg, SN2). ) May need to be moved to.

The PDU SESSION RESOURCE MODIFY INDICATION message includes a “PDU Session Request To Be Modified List” information element (IE). FIG. 13A shows an example of the format of the “PDU Session Request To Be Modified List” IE. As shown in FIG. 13A, the “PDU Session Request To Be Modified List” IE includes “PDU Session Request To Modify Item IEs” IE. “PDU Session Request To Modify Item IEs” IE includes “PDU Session ID” IE and “DL TNL Information” IE. “PDU Session ID” IE indicates the PDU Session ID of each PDU session that requires modification (or modification is required). The "DL TNL Information" IE indicates the downlink (DL) Transport Network Layer (TNL) address and the Tunnel Endpoint Identifier (TEID) for the PDU session specified by the "PDU Session ID" IE. These DL TNL address and TEID specify the RAN node (e.g., gNB) side endpoint of the NG-U tunnel.

Further, in the example of FIG. 13A, the “PDU Session Request To Be Modified List” IE is modified to include the “Modification Type” IE as one of the mandatory information elements (mandatory IEs). The "Modification Type" IE indicates whether the modification of the PDU session specified by the "PDU Session ID" IE is applied to the entire PDU session or a part thereof. For example, “Modification Type” IE indicates “Modify All” or “Modify Partially”. If the "Modification Type" IE is set to "Modify Partially", this indicates a modification to a portion of the PDU session (ie, requesting a PDU session split) and a "PDU Session Request To Be Modified List". "IE" further includes "QoS Flow Request To Be Modified List" IE. The "QoS Flow Request To Be Modified List" IE includes an identifier (i.e., QoS Flow Indicator (QFI)) of each QoS flow transferred from MN1 to SN2. The "QoS Flow Request To Be Modified List" IE may be a "QoS Flow To Be Modified List" IE or a "QoS Flow To Modify List" IE.

Instead of the example of FIG. 13A, as shown in FIG. 13B, the “PDU Session Request To Be Modified List” IE is modified to include a “Modification Type Option” IE as one of mandatory information elements (mandatory IEs). May be. The “Modification Type Option” IE indicates whether the modification of the PDU session specified by the “PDU Session ID” IE is a PDU session split. For example, “Type Option” IE indicates “All” or “Split (or Partial)”. When the “Type Option” IE is set to “Split (or Partial)”, the “PDU Session Request To Be Modified List” IE further includes a “QoS Flow Request To Be Modified List” IE. The "QoS Flow Request To Be Modified List" IE includes an identifier (i.e., QoS Flow Indicator (QFI)) of each QoS flow transferred from MN1 to SN2.

For example, if "Modification Type" IE (Fig. 13A) is set to "Modify Partially", or if "Modification Type Option" IE (Fig. 13B) is set to "Split (or Partial)", AMF /SMF entity 5 recognizes that the PDU session needs to be split into two or more RAN nodes (eg, MN1 and SN2) (or is required to split the PDU session). Good. On the other hand, when the “Modification Type” IE (FIG. 13A) is set to “Modify All” or the “Modification Type Option” IE (FIG. 13B) is set to “All”, the AMF/SMF entity 5 May recognize that the PDU session needs to be moved to another RAN node (eg, SN2) (or is required to move the PDU session to another RAN node) ..

Furthermore, whether the AMF/SMF entity 5 indicates that the PDU session type information (eg, Modification Type IE, or Modification Type Option IE) indicates that PDU session split is required (or required). Accordingly, it may be configured to determine whether the DL TNL address included in the “DL TNL Information” IE is a new DL address or an additional DL address of the PDU session. Specifically, when "Modification Type" IE (Fig. 13A) is set to "Modify Partially" or "Modification Type Option" IE (Fig. 13B) is set to "Split (or Partial)". In this case, the AMF/SMF entity 5 determines that the DL TNL address included in the “DL TNL Information” IE is the additional DL address of the PDU session (ie, the SN2 address corresponding to the added NG-U tunnel). You may judge. On the other hand, when the “Modification Type” IE (FIG. 13A) is set to “Modify All” or the “Modification Type Option” IE (FIG. 13B) is set to “All”, the AMF/SMF entity 5 May determine that the DL TNL address included in the “DL TNL Information” IE is a new DL address of the PDU session.

“MN” and “SN” may be defined instead of the value “All” of “Modification Type Option” IE (FIG. 13B). That is, the "Modification Type Option" IE may be set to any of "MN", "SN", and "Split (or Partial)". For example, if the "Modification Type Option" IE is set to "MN" (or "SN"), the AMF/SMF entity 5 needs to move the PDU session to MN1 (or "SN2"). You may recognize that. When the "Modification Type Option" IE is set to "MN" or "SN", the AMF/SMF entity 5 determines that the DL TNL address included in the "DL TNL Information" IE is the new DL of the PDU session. It may be determined that the address.

Alternatively, the AMF/SMF entity 5 may require a PDU session split depending on whether the "PDU Session Request To Be Modified List" IE contains a "QoS Flow Request To Be Modified List" IE. It may be determined whether or not there is. Specifically, in the AMF/SMF entity 5, the “QoS Flow Request To Be Modified List” IE included in the “PDU Session Request To Be Modified List” IE indicates only a part of the plurality of QoS flows of the PDU session. In some cases, it may be recognized that PDU session split is required. On the other hand, in the AMF/SMF entity 5, the “QoS Flow Request To Be Modified List” IE indicates only a part of the plurality of QoS flows of the PDU session, and the DL TNL address included in the “DL TNL Information” IE is the relevant one. If it matches the DL TNL address for all the remaining QoS flows of the PDU session, it may recognize that the split PDU session is merged into one RAN node.

FIG. 14 shows still another example of the format of the “PDU Session Request To Be Modified List” IE. In the example of FIG. 14, the “PDU Session Request To Be Modified List” IE includes a “Modification Type Option” IE as one of optional elements (optional IEs), and this is set to “Split” as necessary. Has been improved. For example, when the “Modification Type Option” IE is set to “Split” and included in the “PDU Session Request To Be Modified List” IE, the AMF/SMF entity 5 determines that the PDU session has two or more RAN nodes ( eg, MN1 and SN2) may need to be split (or may be required to split the PDU session). On the other hand, when the “Modification Type Option” IE is not included in the “PDU Session Request To Be Modified List” IE, the AMF/SMF entity 5 moves the PDU session to another RAN node (eg, SN2). It may recognize that it is necessary (or requested to move the PDU session to another RAN node). The “Type Option” IE in FIG. 14 may correspond to the above PDU session type information.

Alternatively, the “Modification Type Option” IE in FIG. 14 may be set to either “Split” or “Merge (or Unify)”. For example, when "Modification Type Option" IE is set to "Split", the AMF/SMF entity 5 needs to split the PDU session into two or more RAN nodes (eg, MN1 and SN2). May be recognized. On the other hand, when the "Modification Type Option" IE is set to "Merge (or Unify)", the AMF/SMF entity 5 has split the PDU session into two or more RAN nodes (eg, MN1 and SN2). May be merged into one RAN node.

The "PDU SESSION RESOURCE MODIFY CONFIRM" message includes, for example, a "PDU Session Confirm To Modify List" information element (IE). This indicates a PDU session accepted by the AMF/SMF entity 5 (or a successful PDU session split) among one or more PDU sessions requested for PDU session split by the MN 1. In addition, the "PDU SESSION RESOURCE MODIFY CONFIRM" message is a "PDU Session Not Admitted List" IE (or "PDU Session Not Admitted List" IE (or "PDU Session Failed to Modify List” IE) may be included.

In other implementations, a new NGAP message may be defined for sending the modification request shown in step 1001 of FIG. 10 (and step 1101 of FIG. 11). The new NGAP message requests the core network 4 to split the already set PDU session. In other words, the new NGAP message requests the core network 4 to additionally set up the already configured PDU session to another RAN node (e.g., SN2). For example, the name of the new NGAP message may be a PDU SESSION RESOURCE SETUP INDICATION message or a PDU SESSION RESOURCE ADDITION INDICATION message. Further, the name of the NGAP message from the core network 4 to the RAN node which responds to this may be a PDU SESSION RESOURCE SETUP CONFIRM message or a PDU SESSION RESOURCE ADDITION CONFIRM message.

FIG. 15 shows an example in which a new NGAP message (e.g., PDU SESSION RESOURCE SETUP INDICATION message) is used. In step 1501, the MN 1 sends a PDU SESSION RESOURCE SETUP INDICATION message including a PDU session split request to the AMF/SMF entity 5. In step 1502, the AMF/SMF entity 5 sends a PDU SESSION RESOURCE SETUP CONFIRM message to the MN 1. The PDU SESSION RESOURCE SETUP CONFIRM message corresponds to the response message shown in step 1002 of FIG. 10 (and step 1103 of FIG. 11).

The PDU SESSION RESOURCE SETUP INDICATION message may include a "PDU Session Request To Be Setup List" information element (IE). FIG. 16 shows an example of the format of the “PDU Session Request To Be Setup List” IE. The “PDU Session Request To Be Setup Item IEs” includes “PDU Session Request To Be Setup Item IEs” IE. "PDU Session Request To Be Setup Item IEs" IE includes "PDU Session ID" IE and "DL TNL Information" IE. "PDU Session ID" IE indicates the PDU Session ID of each PDU session split into two or more RAN nodes. "DL TNL Information" IE indicates the DL TNL address and TEID for the PDU session specified by the "PDU Session ID" IE. Further, in the example of FIG. 16, the “PDU Session Request To Be Setup List” IE includes a “QoS Flow Request To Be Modified List” IE. The "QoS Flow Request To Be Modified List" IE includes an identifier (i.e., QoS Flow Indicator (QFI)) of each QoS flow transferred from MN1 to SN2. The name of the “PDU Session Request To Be Setup List” IE may be “PDU Session Request To Be Added List” IE.

As will be understood from the above description, in the present embodiment, the MN 1 is configured to send the already established PDU session modification request to the core network 4, and requires the PDU session split for the established PDU session. The amendment request is configured to include a request (or display or information element) that implicitly or explicitly indicates that the modification is to be performed. Furthermore, the AMF/SMF entity 5 is arranged to receive the modification request. As a result, the AMF/SMF entity 5 should determine whether the PDU session should be split into two or more RAN nodes (eg, MN1 and SN2) when modifying the PDU session, or another RAN node (eg, SN2). ) Can be appropriately determined.

In the PDU session split of the present embodiment, some of the plurality of QoS flows of the PDU session transferred via the MN1 may be transferred to one or more SN2s. More specifically, in the PDU session split of this embodiment, a PDU session already established in MN1 for UE3 is split into MN1 and at least one SN (including SN2) (split over the MN1). and at least one SN including the SN 2) Including cases. Further, in the PDU session split of the present embodiment, the PDU session already established in MN1 for UE3 is moved from MN1 to SN2, and the moved PDU session is split into SN2 and at least one other SN. (Split over the SN 2 and at least one other SN) cases.

Furthermore, in the PDU session split of the present embodiment, some of the plurality of QoS flows of the PDU session transferred via the SN2 may be transferred to the MN1. More specifically, the PDU session split of this embodiment includes a case in which a PDU session already established in SN2 for UE3 is split into SN2 and MN1 (split over the SN2 and the MN1). .. Further, in the PDU session split of the present embodiment, the PDU session already established in SN2 for UE3 is transferred from SN2 to MN1, and the transferred PDU session is split into MN1 and at least one other SN. (Split over the MN 1 and at least one SN) cases are included.

Furthermore, in the PDU session split of the present embodiment, a new QoS flow associated with the PDU session that is set in only one of MN1 and SN2 may be added in the other of MN1 and SN2. In this case, the AMF/SMF entity 5 responds to the reception from MN1 of a request to modify the already established PDU session (which implicitly or explicitly indicates that PDU session split is required). Then, a new QoS flow associated with the already established PDU session may be set. At this time, MN1 and SN2 may map the new QoS flow to the existing data radio bearer (DRB). Alternatively, the MN1 and SN2 may newly establish a DRB and map a new QoS flow to it.

When PDU session splitting is required, the AMF/SMF entity 5 sends one or more specific QoS flows among the plurality of QoS flows associated with the already established PDU session to the MN-1. The UPF entity 6 is controlled to move from the U tunnel to the NG-U tunnel from SN2 (step 1102).

<Second Embodiment>
This embodiment provides another improvement for PDU session splits. A configuration example of the wireless communication network according to this embodiment is the same as the example shown in FIG. 9.

In the present embodiment, the AMF/SMF entity 5 relates to the PDU session in the procedure for establishing the PDU session performed before the transmission of the modification request for the PDU session split described in the first embodiment. An indication on a per PDU session basis (on a per-PDU session basis) or on a per QoS flow basis that indicates whether PDU session split is allowed (or whether PDU session split is possible) is displayed on the RAN node (eg, In the future it will be configured to send to the gNB or eNB which will act as MN1. In the PDU session establishment procedure, the RAN node displays an AMF/indication on a per-PDU session basis or on a per PDU session basis indicating whether or not PDU session split is allowed for the PDU session. It is configured to receive from the SMF entity 5.

The indication may be included in a message sent from the AMF/SMF entity 5 to the RAN node to request the setup of PDU session resources for the PDU session.

In some implementations, the MN 1 is allowed to request the PDU session split from the core network 4 when starting the DC by allowing the PDU session split received during the PDU session establishment procedure. The determination may be made based on the display indicating whether or not to perform.

FIG. 17 is a flowchart showing an example of the operation of the core network 4 according to this embodiment. The procedure of FIG. 17 is performed by the AMF/SMF entity 5. In step 1701, the AMF/SMF entity 5 receives an NGAP message including a NAS message that triggers the establishment of a PDU session for the UE3 from a RAN node (e.g., gNB or eNB that will operate as MN1 in the future). For example, the NAS message may be an Attach Request message for initial attachment to the core network 4 and setup of a default PDU session. In this case, the NGAP message may be an INITIAL UE MESSAGE message. Additionally or alternatively, the NAS message may be a PDU Session Establishment Request message sent by the UE3 to request a new (first or additional) PDU session establishment. In this case, the NGAP message may be an INITIAL UE MESSAGE message or an UPLINK NAS TRANSPORT message.

In step 1702, the AMF/SMF entity 5 controls the UPF entity 6 to set up a PDU session for the UE 3. In step 1703, the AMF/SMF entity 5 determines whether the PDU session split of the newly established PDU session is permitted. In step 1704, the AMF/SMF entity 5 sends to the RAN node a PDU session resource setup request message indicating whether PDU session split is allowed.

FIG. 18 is a sequence diagram showing an example of signaling performed in the PDU session establishment procedure. In step 1801, the RAN node 7 (e.g., gNB or eNB that operates as the MN 1 in the future) sends an NGAP: INITIAL UE MESSAGE message or an NGAP: UPLINK NAS TRANSPORT message to the AMF/SMF entity 5. The NGAP message of step 1801 contains a NAS message (e.g., PDU Session Establishment Request) that triggers the establishment of a PDU session for UE3.

In step 1802, the AMF/SMF entity 5 sends an NGAP:INITIAL CONTEXT SETUP REQUEST message or an NGAP:PDU SESSION RESOURCE SETUP REQUEST message to the RAN node 7. The NGAP message of step 1802 is sent to the RAN node 7 to request the setup of PDU session resources for the PDU session established for UE3. The NGAP message of step 1802 includes an indication on a per-PDU session basis or on a per QoS flow basis indicating whether PDU session splits are allowed for the PDU session. The indication may be, for example, a “PDU Session Split Permission Indication” IE, a “PDU Session Split” IE (which is set to allowed or not-allowed), or a “PDU Session”. Split Support” IE (this may be set to support or not-support).

As will be understood from the above description, in the present embodiment, the AMF/SMF entity 5 uses the PDU session unit indicating whether or not PDU session split is permitted for the PDU session in the PDU session establishment procedure. (On a per-PDU session basis) or configured to send an indication per QoS flow to the RAN node. In the PDU session establishment procedure, the RAN node displays an AMF/indication on a per-PDU session basis or on a per PDU session basis indicating whether or not PDU session split is allowed for the PDU session. It is configured to receive from the SMF entity 5. As a result, the RAN node (ie, the gNB or eNB that operates as the MN 1 in the future) selectively sets the PDU session split to the core network 4 only for the PDU session (or the QoS flow) for which the PDU session split is permitted in advance. It can act to request.

It should be noted that the present embodiment has shown an example in which a display indicating whether or not (or whether or not) PDU session split is permitted in units of PDU session or QoS flow is used. This limits the AMF/SMF entity 5 so that the determination of whether to allow PDU session split (or support of whether or not PDU session split is possible) is performed on a PDU session basis or a QoS flow basis. is not. That is, the indication is sent for each PDU session that is established (that is, establishment is required) (or for each QoS flow), but the content of the indication is a plurality of items controlled by the AMF/SMF entity 5. It may be common between the PDU session and the multiple QoS flows contained in it.

<Third Embodiment>
This embodiment provides a modification of the second embodiment. A configuration example of the wireless communication network according to this embodiment is the same as the example shown in FIG. 9.

The AMF/SMF entity 5 may send an indication on a per UE basis to the RAN node 7 indicating whether (or whether or not) PDU session split is allowed. In this case, the AMF/SMF entity 5 may determine whether or not to allow the PDU session split on a UE basis. In some implementations, the AMF/SMF entity 5 sends to the RAN node 7 an indication on a per UE basis in the PDU session establishment procedure for the UE 3 indicating whether or not PDU session split is allowed for the UE 3. May be.

As a result, the RAN node 7 (ie, gNB or eNB that operates as the MN 1 in the future) selectively cores the PDU session split only for the PDU session (or QoS flow) of the UE 3 for which the PDU session split is permitted in advance. It can operate to request the network 4.

<Fourth Embodiment>
This embodiment provides another improvement for PDU session splits. A configuration example of the wireless communication network according to this embodiment is the same as the example shown in FIG. 9.

In the present embodiment, the AMF/SMF entity 5 uses the RAN node (eg, gNB that operates as MN1 in the future, or RAN node) that is performed before the transmission of the modification request for the PDU session split described in the first embodiment. eNB) and AMF/SMF entity 5 in the procedure of setting up or modifying the signaling connection (ie, NG2/NG-C interface), whether PDU session split is allowed (or PDU session It is configured to send an indication indicating whether splitting is possible) to the RAN node. The RAN node AMF displays an indication indicating whether or not PDU session split is permitted (or whether or not PDU session split is possible) in the procedure for setting up or modifying the signaling connection with the AMF/SMF entity 5. /Configured to receive from SMF entity 5.

The display may be a display in AMF/SMF units. Alternatively, the indication may indicate whether PDU session splits are allowed or disallowed (or enabled or disabled) for each UPF. Additionally or alternatively, the indication may indicate whether PDU session splits are allowed or disallowed (or enabled or disabled) for each network slice.

In addition, 5G System supports network slicing. Network slicing uses Network Function Virtualization (NFV) technology and software-defined networking (SDN) technology to enable multiple virtualized logical networks to be created on top of a physical network. Each virtualized logical network is called a network slice or a network slice instance, which contains logical nodes and functions and is used for specific traffic. And used for signaling. NG-RAN or 5GC or both have Slice Selection Function (SSF). The SSF selects one or more network slices suitable for the 5G UE based on information provided by at least one of the 5G UE and the 5GC.

Therefore, in some implementations, the core network 4 may provide multiple network slices. The plurality of network slices are distinguished by, for example, a service or use case provided to the UE 3 on each network slice. The use cases include, for example, broadband communication (enhanced Mobile Broad Band: eMBB), highly reliable and low latency communication (Ultra Reliable and Low Latency Communication: URLLC), and multi-connection M2M communication (massive Machine Type Communication: mMTC). These are called slice types (e.g., Slice/Service Type (SST)).

Further, MN1 or SN2 or both may support one or more network slices. In other words, one or more network slices may be available in the cells of MN1 and SN2. In some implementations, MN1 or SN2, or both, call a Core Network (CN) slice of the core network 4 selected for UE3 to provide end-to-end network slicing to UE3. ) And a radio slice may be allocated to UE3.

By the above-mentioned display sent from the AMF/SMF entity 5 to the RAN node (eg, gNB or eNB that will operate as MN 1 in the future) indicating whether the PDU session split is permitted or not for each network slice (CN slice), for example, , Offers several advantages:

For example, the MN 1 may consider whether or not each CN slice permits PDU session split when making a CN slice selection for the UE 3. Thereby, for example, the MN 1 can select the CN slice in which the PDU session split is permitted for the UE 3 which is scheduled to execute the DC in the future.

Further, for example, the MN 1 can selectively request the PDU session split to the core network 4 only for the PDU session that uses the CN slice for which the PDU session split is permitted in advance.

Further, for example, when the MN 1 starts a DC for a PDU session using a CN slice for which PDU session split is not permitted, the MN 1 requests the core network 4 to switch the PDU session to another CN slice. be able to.

FIG. 19 is a flowchart showing an example of the operation of the core network 4 according to this embodiment. The procedure of FIG. 19 is performed by the AMF/SMF entity 5. In step 1901, the AMF/SMF entity 5 receives the NG interface setup request from the RAN node (e.g., gNB or eNB which will operate as the MN 1 in the future). In step 1902, the AMF/SMF entity 5 sends an NG interface setup response message indicating whether PDU session split is allowed (or whether PDU session split is possible) to the RAN node (eg, MN1). ) To.

FIG. 20 is a sequence diagram showing an example of signaling performed in the NG setup procedure. The NG setup procedure enables the RAN node 7 (e.g., gNB or eNB that will act as MN 1 in the future) and the AMF/SMF entity 5 to correctly interoperate on the N2 interface (NG-C interface).

In step 2001, the RAN node 7 sends an NG SETUP REQUEST message to the AMF/SMF entity 5. In step 2002, the AMF/SMF entity 5 sends an NG SETUP RESPONSE message to the RAN node 7. The NG SETUP RESPONSE message includes an indication indicating whether PDU session split is allowed. The indication may be, for example, a “PDU Session Split Permission Indication” IE, a “PDU Session Split” IE (this is set to allowed or not-allowed), or a “PDU Session”. Split Support” IE (this may be set to support or not-support). As described above, the display may indicate permission or disapproval (or enable/disable) of the PDU session split for each network slice (CN slice).

As can be understood from the above description, in the present embodiment, the AMF/SMF entity 5 uses the RAN display in the NG setup procedure to indicate whether or not (or whether or not) PDU session split is permitted. It is configured to send to the node. The RAN node is configured to receive an indication from the AMF/SMF entity 5 in the NG setup procedure indicating whether PDU session split is allowed. As a result, the RAN node (i.e., gNB or eNB that operates as the MN 1 in the future) can operate to request the PDU session split from the core network 4 only when the PDU session split is previously permitted.

<Fifth Embodiment>
This embodiment provides another improvement for PDU session splits. A configuration example of the wireless communication network according to this embodiment is the same as the example shown in FIG. 9.

In this embodiment, the MN1 requests to allocate resources for the PDU session (and the QoS flow(s) of the PDU session) used in the dual connectivity (DC) for the UE3, the secondary cell group (SCG). It is configured to send an add request message to SN2. SN2 is configured to receive the SCG addition request message from MN1. Furthermore, the SCG addition request message implicitly or explicitly indicates that the PDU session split is applied to the PDU session already established between the UE 3 and the UPF entity 6 in the core network 4. The SCG addition request message may be an SgNB ADDITION REQUEST message (or SN ADDITION REQUEST message).

In some implementations, the SCG add request message may include a PDU session establishment type information (eg, PEG session split type) that explicitly indicates that the PDU session split is applied to the PDU session or one or more QoS flows of the PDU session. , "PDU Session Establishment Type" Information Element (IE)). For example, the PDU session establishment type information may be one of the optional elements (optional IEs) included in the SCG addition request message. In this case, the SN2 recognizes that PDU split is applied to the PDU session if the PDU session establishment type information is included in the SCG addition request message (or if it is set to "Split"). May be.

FIG. 21 is a flowchart showing an example of the operation of MN1. In step 2101, MN1 sends an SCG addition request message to SN2 in order to move some of the plurality of QoS flows of the already established PDU session to SN2. The SCG addition request message requests to allocate resources for the PDU session (and the QoS flow(s) of the PDU session) used in the DC for UE3 and indicates the PDU session split. In step 2102, SN2 receives a response message (e.g., SN ADDITION REQUEST ACKNOWLEDGE message) from SN2.

FIG. 22 is a sequence diagram showing an example of signaling performed in the SgNB (or SN) addition preparation procedure. In step 2201, MN1 sends a SN ADDITION REQUEST message to SN2. The SN ADDITION REQUEST message includes a "PDU Session ID" information element (IE), a "PDU Session Establishment Type" IE and a "QoS Flow List" IE. “PDU Session ID” IE is a PDU session transferred from MN1 (ie, MCG) to SN2 (ie, SCG), UPF entity 6 to MN1 (ie, MCG) and SN2 (ie, SCG) by AMF/SMF entity 5. It indicates at least one of the PDU session established in MN1 (ie, MCG) split into two or the PDU session newly established in SN2 (ie, SCG). "PDU Session Establishment Type" IE indicates whether or not PDU session split is applied to the PDU session added to SN2. The “QoS Flow List” IE is included in the PDU session added to SN2 and is moved from MN1 (ie, MCG) to SN2 (ie, SCG) or newly established in SN2 (ie, SCG) 1 Or more QoS flows.

The SN ADDITION REQUEST message further includes “Bearer Option” IE as one of essential information elements (mandatory IEs). “Bearer Option” IE indicates the type of data radio bearer (DRB) to be set in SCG (i.e., SCG bearer, MCG split bearer, or SCG split bearer). Therefore, the above-mentioned “PDU Session Establishment Type” IE and “QoS Flow List” IE may be associated with the “Bearer Option” IE indicating the SCG bearer or the SCG split bearer. In other words, the “PDU Session Establishment Type” IE and the “QoS Flow List” IE described above may be included in the “Bearer Option” IE indicating the SCG bearer or the SCG split bearer. Note that the MCG split bearer and SCG split bearer may be collectively referred to as a split bearer, or may be referred to as Split bearer anchored at MN (MCG) and Split bearer anchored at SN (SCG).

The SN ADDITION REQUEST message includes information (i.e., RRC: SCG-ConfigInfo) related to secondary cell group (SCG) configuration. For example, the information related to the SCG setting includes a list of DRBs requested to be added from MN1 to SN2. The DRB list indicates the association of the PDU session identifier (i.e., PDU Session ID), the DRB identifier (i.e., DRB Identity), and one or more QoS flow identifiers (i.e., QFIs) in the MCG. Instead, the information related to the SCG setting is the identifier of the PDU session (ie, PDU Session ID) requested to be added from MN1 to SN2, and the identifier of one or more QoS flows (ie, QFIs). May be shown. Further, the information related to the SCG setting may include information (e.g., PDU session type information or DRB type information) that explicitly indicates the PDU session split. Further, the information related to the SCG configuration may include at least a part of the master cell group (MCG) configuration (e.g. MCG Configuration) for the UE3 by the MN1. For example, the MCG settings include individual radio resource settings (e.g., “RadioResourceConfigDedicatedMCG” IE) of each MCG cell. The individual radio resource setting of each MCG cell includes a list of already established DRBs. The DRB list indicates the association of a PDU session identifier (i.e., PDU Session ID), a DRB identifier (i.e., DRB Identity), and one or more QoS flow identifiers (i.e., QFIs). The MCG setting may include information (e.g., PDU session type information or DRB type information) that explicitly indicates the PDU session split.

In step 2202, SN2 sends a SN ADDITION ACKNOWLEDGE message to MN1. The SN ADDITION ACKNOWLEDGE message includes a secondary cell group (SCG) configuration (i.e., RRC: SCG-Config). The SCG settings are the SCG cell list to be added (ie, Primary Secondary Cell (PSCell) and zero or more SCG SCell(s)), and individual radio resource settings for each SCG cell (eg, “ RadioResourceConfigDedicatedSCG"IE) is included. The individual radio resource setting of each SCG cell includes a list of DRBs to be added, and the DRB list includes a PDU session identifier (ie, PDU Session ID), a DRB identifier (ie, DRB Identity), and one or more Indicates the association of QoS flow identifiers (ie, QFIs). The SCG setting may include information (e.g., PDU session type information or DRB type information) that explicitly indicates the PDU session split.

Here, instead of or together with the PDU session identifier, the identifier of the SDAP entity associated with the PDU session (eg, SDAP Identity, or Service Channel Identity indicating the association between the SDAP layer and the PDCP layer) is used. May be. For example, the Service Channel Identity may be defined as a Service Access Point (SAP) between the SDAP entity and each PDCP entity connected to it. Also, the identifier of the SDAP entity may be assigned by MN1, which notifies SN2 as one of the information elements (eg, RRC: SDAP-Config of SCG-ConfigInfo) included in the SN ADDITION REQUEST message, SN2 may use it. Further, SDAP entities associated with the same PDU session split PDU session identifier may be assigned the same SDAP entity identifier.

The movement (i.e., offloading) of one or more QoS flows from MN1 to SN2 may be performed in DRB units or in QoS flow units. In DRB-based offloading, all QoS flows of one MCG bearer or MCG split bearer are transferred to the SCG bearer or SCG split bearer. The SCG bearer or SCG split bearer corresponding to the DRB to which the QoS flow is mapped (included) is newly established in the SN Addition procedure. At this time, SN2 (i.e., SCG) makes the same setting as the mapping (inclusive relationship) between the QoS flow and DRB in MN1 (i.e., MCG). Furthermore, the SN2(ie, SCG) also moves other QoS flows newly established in the SN2(ie, SCG) during the SN Addition procedure from the MN1(ie, MCG) to the SN2(ie, SCG). May be mapped to the same DRB. Alternatively, the multiple QoS flows that were mapped to the same DRB in MN1 (i.e., MCG) may be mapped to different DRBs in SN2 (i.e., SCG). The mapping between the QoS flow and DRB in these SN2 (ie, SCG) may be designated by MN1 to SN2, or MN1 notifies SN2 of the mapping between the QoS flow and DRB in MCG and finally May be determined by SN2.

As can be understood from the above description, in this embodiment, the MN1 is configured to send the SN2 an SCG addition request message requesting allocation of resources for the DC for the UE3. SN2 is configured to receive the SCG addition request message from MN1. Furthermore, the SCG addition request message implicitly or explicitly indicates that the PDU session split is applied to the PDU session already established between the UE 3 and the UPF entity 6 in the core network 4. This provides several advantages, for example:

For example, SN2 is allowed to map multiple QoS flows of the same PDU session to one DRB. Therefore, the SN 2 can perform the same DRB mapping of the QoS flow to which the PDU session split of the same PDU session is applied and the QoS flow of the MCG split bearer.

Further, for example, when the SN2 further transfers the QoS flow from the SN2 to another SN or returns the QoS flow from the SN2 to the MN1, the SN2 indicates that the PDU session split is applied to the QoS flow. Or it can inform MN1.

<Sixth Embodiment>
This embodiment provides a modification of the interaction between MN1 and SN2 shown in the fifth embodiment. A configuration example of the wireless communication network according to this embodiment is the same as the example shown in FIG. 9.

The MN1 uses the SCG in order to allocate or modify the resources for the PDU session (and the QoS flow(s) of the PDU session) used in dual connectivity (DC) for the UE3. An inter-base station (or inter-node) message (eg, XnAP message) different from the addition request message may be sent to SN2. For example, the MN 1 may send a secondary cell group (SCG) modification preparation request message. The SCG modification preparation request message may be an SgNB MODIFICATION REQUEST message (or SN MODIFICATION REQUEST message). The SCG modification preparation request message requests SN2 to modify one or more SCG cells (ie, PSCell, SCG SCell(s), or PSCell and SCG SCell(s)) already configured for UE3. .. The SCG modification preparation request message can be used to transfer a part of the plurality of QoS flows of the PDU session already established for UE3 from MN1 to SN2. Additionally or alternatively, the SCG modification preparation request message can be used to transfer some of the plurality of QoS flows of the already established PDU session for UE3 from SN2 to MN1. In this case, the SCG modification preparation request message may implicitly or explicitly indicate that the PDU session split is applied to the already established PDU session.

As described in the fifth embodiment, movement (ie, offloading) of one or more QoS flows from MN1 to SN2 may be performed in DRB units or in QoS flow units. May be done. In DRB-based offloading, all QoS flows of one MCG bearer or MCG split bearer are transferred to the SCG bearer or SCG split bearer. The SCG bearer or SCG split bearer corresponding to the DRB to which the QoS flow is mapped (included) may be newly established in the SN Modification procedure or may be already established.

Similarly, movement (i.e., offloading) of one or more QoS flows from SN2 to MN1 may be performed in DRB units or in QoS flow units. In DRB-based offloading, all QoS flows of one SCG bearer or SCG split bearer are moved to the MCG bearer or MCG split bearer. The MCG bearer or MCG split bearer corresponding to the DRB to which the QoS flow is mapped (included) may be newly established in the SN Modification procedure or may be already established.

The interaction between MN1 and SN2 described in the present embodiment is also applied when merging (integrating) the split PDU session (and the QoS flow(s) of the PDU session) into one RAN node. be able to. For example, a PDU session split from MN1 to SN2 may be merged into MN1 again. Alternatively, all the QoS flows remaining in MN1 of the PDU session split from MN1 to SN2 may be moved to SN2. Similarly, a PDU session split from SN2 to MN1 may be merged into SN2 again. Alternatively, all the QoS flows remaining in SN2 of the PDU session split from SN2 to MN1 may be moved to MN1.

The SN Modification procedure for SCG modification including the SCG modification preparation request message may be initiated from MN1 itself. Alternatively, it may be initiated from SN2 by sending an SCG modification request message requesting MN1 to perform the SN Modification procedure. The SCG modification request message may be an SgNB MODIFICATION REQUIRED message (or SN MODIFICATION REQUIRED message).

Furthermore, the information elements included in the SCG addition request message described in the fifth embodiment may be included in the SCG correction preparation request message, the SCG correction request message, or both. Furthermore, the name or configuration of each information element may be different. For example, "PDU Session Establishment Type" IE may be replaced with "PDU Session Modification Type" IE. Also, PDU session establishment type information (eg, "PDU Session Establishment Type" information element (IE)) is set to "Split" in the case of PDU session split, and the split PDU sessions are merged (integrated). In some cases, it may be set to "Merge (or Unify)".

Here, instead of or together with the PDU session identifier, the identifier of the SDAP entity associated with the PDU session (eg, SDAP Identity, or Service Channel Identity indicating the association between the SDAP layer and the PDCP layer) is used. May be. For example, the Service Channel Identity may be defined as a Service Access Point (SAP) between the SDAP entity and each PDCP entity connected to it. For example, the Service Channel Identity may be defined as a Service Access Point (SAP) between the SDAP entity and each PDCP entity connected to it. Further, the identifier of the SDAP entity may be assigned by the MN1, which notifies the SN2 as one of the information elements (eg, RRC: SDAP-Config of SCG-ConfigInfo) included in the SN MODIFICATION REQUEST message, SN2 may use it. Further, SDAP entities associated with the same PDU session split PDU session identifier may be assigned the same SDAP entity identifier.

<Seventh Embodiment>
This embodiment provides another improvement for PDU session splits. A configuration example of the wireless communication network according to this embodiment is the same as the example shown in FIG. 9.

In the present embodiment, MN1 or SN2 is configured to send an RRC connection reconfiguration message indicating a secondary cell group (SCG) setting for DC to UE3. UE3 is configured to receive the RRC connection reconfiguration message from MN1 or SN2. The RRC connection reconfiguration message is further transmitted to one or more QoS flows transferred from MN1 (ie, MCG) to SN2 (ie, SCG), or one or more data radio bearers (DRB) in a PDU session Implicitly or explicitly indicate that the split applies. In other words, the RRC connection reconfiguration message implicitly or explicitly indicates that the PDU session split is applied to the PDU session already established between the UE 3 and the core network 4.

As an example, in order to implicitly or explicitly indicate the PDU session split, the configuration information (eg, SCG Configuration) of the secondary cell group included in the RRC connection reconfiguration message is information related to the PDU session (eg, PDU session identifier). , PDU session type information). For example, the setting information of the secondary cell group includes the identifier (ie, PDU Session ID) of the PDU session already established in the master cell group (MCG), and the MN included in the PDU session and from MN1 (ie, MCG) to SN2 ( ie, SCG), one or more QoS flows may be associated with a data radio bearer containing the QoS flow.

For example, in order to implicitly indicate the PDU session split, the setting information (eg, “SCG Configuration” IE) of the secondary cell group (SCG) of the DRB(s) established in the SCG (eg , “DRB-ToAddModSCG” IE) may include a PDU session identifier (ie, PDU Session ID), a QoS flow identifier (ie, QoS Flow Indicator (QFI)), and a DRB identifier (ie, DRB Identity). The DRB(s) setting information (e.g., “DRB-ToAddModSCG” IE) established in the SCG may further include corresponding DRB type information (e.g., MCG split, SCG, SCG split).

Instead, in order to explicitly indicate the PDU session split, the setting information of the DRB(s) established in the SCG (eg, “SCG Configuration” IE) in the setting information of the SCG (eg, “ DRB-ToAddModSCG" IE) may include PDU session type information (eg, PDU-SessionType (set to "split")). The PDU session type information may be set to "non-split" if it is not a PDU session split. Alternatively, the PDU session type information may be included only in the case of PDU session split. Further, the DRB(s) setting information corresponds to a PDU session identifier (ie, PDU Session ID), a QoS flow identifier (ie, QoS Flow Indicator (QFI)), and a DRB identifier (ie, DRB Identity), and corresponding. DRB type information (eg, MCG split, SCG, SCG split) may be included.

Further or alternatively, the configuration information (eg, SCG Configuration) of the secondary cell group (SCG) is used to explicitly indicate the PDU session split, and the PDU session already established in the MCG or one or more It may include an indication explicitly that the PDU session split applies to the QoS flow. The display may be, for example, data radio bearer type information. The data radio bearer type information indicates a data radio bearer type indicating that PDU session split is applied, for example, “PDU session Split (PS) SCG bearer” or “PDU session Split (PS) SCG split bearer”. Good.

In addition, all or some of the information elements (IEs) included in the setting information (e.g., SCG Configuration) of the above-described secondary cell group (SCG) may be generated by SN2 and transferred from SN2 to MN1. Further, the MN 1 may transparently transmit the information element to the UE 3, and the UE 3 may receive it by the MCG.

Furthermore, the above-mentioned RRC connection reconfiguration (Reconfiguration) message may include configuration information (e.g., MCG Configuration) of the master cell group. The configuration information (e.g., MCG Configuration) of the master cell group may be transmitted in one RRC connection reconfiguration (Reconfiguration) message together with the configuration information (e.g., SCG Configuration) of the secondary cell group (SCG) described above. At least part of the information elements (eg, PDU session identifier and PDU session type information) included in the above-mentioned configuration information (eg, SCG Configuration) of the secondary cell group (SCG) is the configuration information of the secondary cell group (SCG). Instead of (eg, SCG Configuration), it may be included in the configuration information (eg, MCG Configuration) of the master cell group. For example, the configuration information of the master cell group (MCG) includes the identifier (ie, PDU Session ID) of the PDU session already established in the master cell group and the MN included in the PDU session and from MN1 (ie, MCG) to SN2 ( ie, SCG), one or more QoS flows that are not moved to a data radio bearer that includes the QoS flow.

23 and 24 are flowcharts showing an example of the operation of the MN 1. In Step 2301 and Step 2401, the MN 1 requests the SCG configuration for DC and executes the RRC Connection Reconfiguration message indicating the PDU session split to the UE 3. That is, the RRC Connection Reconfiguration message includes an indication of PDU session split and SCG-Configuration. An indication of PDU session split may be included in the SCG-Configuration. In Step 2302 and Step 2402, the MN 1 receives the RRC Connection Reconfiguration Complete message from the UE 3. The RRC Connection Reconfiguration message may be transmitted to the UE3 via the SN2 (in the i.e. SCG cell) using the MCG Split SRB split from the MN1 to the SN2. Instead, of the information included in the RRC Connection Reconfiguration message, the SN2 sends an SCG RRC Connection Reconfiguration message requesting at least SCG configuration for DC and including PDU session split information to the SCG. You may transmit to UE3 using SRB.

FIG. 25 shows an example of interaction between the NAS layer 31 of the UE 3 and the Access Stratum (AS) layer 32. If the AS layer 32 receives the RRC Connection Reconfiguration message (step 2401 in FIG. 24) including information implicitly or explicitly indicating that the PDU session split is applied to the already established PDU session from the MN 1, Notify the upper layer (ie, NAS layer 31) of an indication (eg, PDU Session Split Indication) indicating that PDU session split is applied and the corresponding PDU session identifier (ie, PDU Session ID) (indicate to upper layer). At this time, the AS layer 32 may also notify the NAS layer 31 of a QoS flow identifier (i.e., QoS flow Indicator (QFI)). Further or alternatively, the AS layer 32 updates mapping information indicating that one or more QoS flows belonging to an already established PDU session are transferred to the DRB (ie, SCG bearer or SCG split bearer) of the SCG. May be notified to the upper layer (ie, NAS layer 31) (indicate to upper layer). As a result, the NAS layer 31 can recognize that a plurality of QoS flows belonging to the same PDU session are split into MN1 (MCG) and SN2 (SCG).

Alternatively, when the PDU session split is implicitly indicated in the MR-DC, the AS layer 32 (eg, the RRC layer of the SCG RAT) of the UE 3 establishes the data radio bearer (DRB), the relevant DRB. The QoS flow identifier and the PDU session identifier corresponding to the above may be indicated in the upper layer (UE NAS layer 31). In this case, the upper layer splits the PDU session based on the fact that the PDU session identifier already overlaps with the PDU session identifier indicated by the AS layer 32 (eg, RRC layer of MCG RAT). May be recognized. For example, in the PDU session establishment request procedure of the PDU session started (triggered) by the NAS layer 31 of the UE 3, the NAS layer 31 assigns the PDU session ID. Therefore, the NAS layer 31 has the same PDU session ID as the one already assigned to the AS layer 32 of the RAT (eg, MCG RAT) of one cell group (CG), but the RAT of another CG (eg, SCG RAT). It is possible to recognize that the PDU session is split when it is indicated from the AS layer 32.

Alternatively, each of MCG-configuration and SCG-configuration within the same RRC Connection Reconfiguration may include a PDU session identifier. In this case, the UE 3 recognizes that the PDU session is split based on the fact that the PDU session identifier in the MCG-configuration and the PDU session identifier in the SCG-configuration overlap (are the same). Good. In one example, the UE AS layer 32 may recognize the PDU session split based on the duplication of the PDU session identification, and then notify the UE NAS layer 31 that the PDU session identifier or the PDU session split has been performed. Instead, the UE NAS layer 31 receives the PDU session identifier in the MCG-configuration and the PDU session identifier in the SCG-configuration from the UE AS layer 32, and based on these two PDU session identifiers, PDU session split You may recognize that it is being done.

Here, instead of or together with the PDU session identifier, the identifier of the SDAP entity associated with the PDU session (eg, SDAP Identity, or Service Channel Identity indicating the association between the SDAP layer and the PDCP layer) is used. May be. As described above, the Service Channel Identity may be defined as a Service Access Point (SAP) between the SDAP entity and each PDCP entity connected to it.

<Eighth Embodiment>
This embodiment provides improvements for UE mobility when NR-NR DC with PDU session split is performed. A configuration example of the wireless communication network according to this embodiment is the same as the example shown in FIG. 9.

In the present embodiment, consider the following three mobility scenarios.

1. Change of SgNB
The first mobility scenario is Change of SgNB (or SgNB Change). This scenario is similar to the Change of SeNB scenario at DC in 3GPP Release 12 (LTE-Advanced). That is, the Change of SgNB procedure is initiated by MgNB (ie, MN1), transfers the UE context (UE context) from the source SgNB (ie, SN2) to the target SgNB and has the SCG configuration (SCG config) in the UE. It is used to change the setting generated (designated) by SgNB to the setting generated (designated) by another SgNB.

The MgNB (i.e., MN1) initiates the Change of SgNB by requesting the target SgNB to allocate resources for UE3 using the SgNB (or SN) addition preparation procedure. The SgNB (or SN) addition preparation procedure is basically as shown in the fifth embodiment (FIGS. 21 and 22). The difference is that the UE context transferred by the MgNB to the target SgNB includes the SCG setting generated (specified) by the source SgNB. After performing the SgNB (or SN) addition preparation procedure, the MgNB (ie, MN1) is described in the first embodiment to notify the UPF entity 6 of the update of the DL TNL information (DL TNL address and TEID). Also, a message for requesting modification of an already established PDU session (indicating necessity of PDU session split) may be sent to the AMF/SMF entity 5.

2. MgNB to gNB Change
The second mobility scenario is MgNB to gNB Change. This scenario is similar to the MeNB to eNB Change scenario at DC in 3GPP Release 12 (LTE-Advanced). That is, the MgNB to gNB Change procedure is used to transfer context data from the source MgNB (ie, MN1) and the source SgNB (ie, SN2) to the target gNB.

The source MgNB (i.e., MN1) starts the MgNB to gNB Change procedure by starting the Xn Handover Preparation procedure. That is, the source MgNB (i.e., MN1) sends the Xn: HANDOVER REQUEST message to the target gNB. The source MgNB (i.e., MN1) includes the SCG configuration information (SCG configuration) in the handover preparation information (“HandoverPreparationInformation” IE) in the HANDOVER REQUEST message. The setting information of the SCG indicates the association of a PDU session identifier (i.e., PDU Session ID), a DRB identifier (i.e., DRB Identity), and one or more QoS flow identifiers (i.e., QFIs). The SCG setting may include information (e.g., PDU session type information or DRB type information) that explicitly indicates the PDU session split.

FIG. 26 is a sequence diagram showing an example of signaling performed in the Xn Handover Preparation procedure. In step 2601, the source MgNB (i.e., MN1) sends a HANDOVER REQUEST message to the target gNB8. As described above, the HANDOVER REQUEST message includes SCG setting information. Further, the HANDOVER REQUEST message may include information (e.g., PDU session type information or DRB type information) that explicitly indicates the PDU session split. The type information may be included in the SCG setting information.

3. Inter-MgNB handover without SgNB change
The third mobility scenario is Inter-MgNB handover without SgNB change. This scenario is similar to the Inter-MeNB handover without SeNB change scenario in DC of 3GPP Release 12 (LTE-Advanced). That is, the Inter-MgNB handover without SgNB change procedure is used to transfer context data from the source MgNB (ie, MN1) to the target MgNB to which SgNB is added during handover.

The source MgNB (i.e., MN1) starts the Inter-MgNB handover without SgNB change procedure by starting the Xn Handover Preparation procedure. That is, the source MgNB (i.e., MN1) sends the Xn: HANDOVER REQUEST message to the target MgNB. The source MgNB (i.e., MN1) includes the SCG configuration (“SCG configuration” IE) in the handover preparation information (“HandoverPreparationInformation” IE) in the HANDOVER REQUEST message. Furthermore, the source MgNB (i.e., MN1) includes the SgNB UE XnAP ID and SgNB ID in the “UE Context Reference at the SgNB” IE in the HANDOVER REQUEST message. These SgNB UE XnAP ID and SgNB ID are used to identify data and signaling messages regarding the UE 3 in the Xn interface of SgNB (i.e., SN2).

The “SCG configuration” IE or the “UE Context Reference at the SgNB” IE may include information (e.g., PDU session type information or DRB type information) that explicitly indicates the PDU session split. Similarly to the example illustrated in FIG. 26, the source MgNB (i.e., MN1) may send the HANDOVER REQUEST message to the target MgNB8. The HANDOVER REQUEST message includes "SCG configuration" IE and "UE Context Reference at the SgNB" IE. Further, the HANDOVER REQUEST message may include information (e.g., PDU session type information or DRB type information) that explicitly indicates the PDU session split. The type information may be included in the “SCG configuration” IE or the “UE Context Reference at the SgNB” IE.

In the MgNB to gNB Change procedure, the NG-U tunnel to the source MgNB (ie, MN1) and the NG-U tunnel to the source SgNB (ie, SN2) are changed to the NG-U tunnel to the target gNB. , The target gNB requests the Path switch of the DL GTP tunnel (ie, NG-U (or N3) tunnel) of each PDU session to the AMF/SMF entity 5, and the AMF/SMF entity 5 makes NG-U (or N3). Perform the Path Switch procedure. Furthermore, even in the Inter-MgNB handover without SgNB change procedure, in order to change the NG-U tunnel to the source MgNB (ie, MN1) to the NG-U tunnel to the target MgNB, the target gNB is NG-U (or N3 ) Path switch of AMF/SMF entity 5 and the AMF/SMF entity 5 executes the NG-U (or N3) Path Switch procedure.

The NG-U (or N3) Path Switch procedure is similar to the S1 Path Switch procedure at 3GPP Release 12 (LTE-Advanced) DC. That is, as shown in FIG. 27, the target (M)gNB 8 sends a PATH SWITCH REQUEST message to the AMF/SMF entity 5. The PATH SWITCH REQUEST message may include type information (e.g., PDU session type information or QoS flow type information) that explicitly indicates the PDU session split. Alternatively, the target (M)gNB 8 may request the NG-U (or N3) Path Switch for each NG-U (or N3) split from one PDU session.

When the PATH SWITCH REQUEST message including the type information is received in the MgNB to gNB Change procedure, the AMF/SMF entity 5 transmits the NG-U tunnel to the source MgNB (ie, MN1) to which the PDU session split is applied and It is decided to change the NG-U tunnel to the source SgNB (ie, SN2) to the NG-U tunnel to the target gNB8. On the other hand, when the PATH SWITCH REQUEST message including the type information is received in the Inter-MgNB handover without SgNB change procedure, the AMF/SMF entity 5 sends to the source MgNB (ie, MN1) to which the PDU session split is applied. It decides to change the NG-U tunnel to an NG-U tunnel to the target MgNB8 and recognizes that the PDU session split is applied to the NG-U tunnel to the target MgNB8.

Instead, the PATH SWITCH REQUEST message explicitly states that the relationship between the PDU session established before the handover, the QoS flow of the PDU session, and the corresponding RAN node (source MgNB1, SgNB2) is maintained. The information element shown in may be included. The information element may be, for example, "relative PDU session mapping kept" IE. In other words, the AMF/SMF entity 5 receives the information element, and thereby the PDU session established in the source MgNB1 and the QoS flow of the PDU session are established in the target MgNB8 and the SgNB2. It can be recognized that the PDU session and the QoS flow of the PDU session are maintained in the SgNB2 as they are.

<Ninth Embodiment>
The plurality of embodiments described above may be implemented independently or may be implemented in combination as appropriate. For example, as described above, the MN 1 is for the PDU session to which the PDU session split is applied according to the SN ADDITION procedure described in the fifth embodiment or the SN MODIFICATION procedure described in the sixth embodiment. May request the resource allocation of SN2 to SN2. After that, the MN 1 may send a request to modify the already established PDU session to the AMF/SMF entity 5, as described in the first embodiment.

Further or alternatively, when the MN1 is requested to add a new QoS flow by the AMF/SMF entity 5, the MN1 does not map the new QoS flow to the DRB of the MN1 (MCG), but the new QoS flow. May be directly mapped to the DRB of SN2 (SCG). More specifically, the AMF/SMF entity 5 sends an NGAP: PDU SESSION RESOURCE MODIFY REQUEST message to MN1 to request the addition of a new QoS flow to the already established PDU session for UE3. In response to receiving the NGAP message, the MN 1 allocates resources for the new QoS flow according to the SN ADDITION procedure described in the fifth embodiment or the SN MODIFICATION procedure described in the sixth embodiment. You may request SN2. The SN2 may establish a new SCG bearer for the new QoS flow or may map the new QoS flow to an existing SCG bearer. In other words, SN2 may determine the bearer to SCG to which the new QoS flow is mapped. For example, in NR-NR DC, MN1 or SN2 may determine the mapping of a new QoS flow and SCG bearer, and in MR-DC, SN2 may determine the mapping. After the SN ADDITION procedure or the SN MODIFICATION procedure, the MN 1 may send a modification request of the already established PDU session to the AMF/SMF entity 5 according to the procedure described in the first embodiment.

Next, in the following, configuration examples of the MN1, SN2, UE3, and AMF/SMF entity 5 according to the above-described embodiments will be described. FIG. 28 is a block diagram showing a configuration example of the MN 1 according to the above embodiment. The configuration of SN2 may be the same as that shown in FIG. Referring to FIG. 28, the MN 1 includes a Radio Frequency transceiver 2801, a network interface 2803, a processor 2804, and a memory 2805. The RF transceiver 2801 performs analog RF signal processing to communicate with UEs including UE3. The RF transceiver 2801 may include multiple transceivers. RF transceiver 2801 is coupled with antenna array 2802 and processor 2804. The RF transceiver 2801 receives the modulation symbol data from the processor 2804, generates a transmission RF signal, and supplies the transmission RF signal to the antenna array 2802. The RF transceiver 2801 also generates a baseband reception signal based on the reception RF signal received by the antenna array 2802, and supplies this to the processor 2804.

The network interface 2803 is used to communicate with the network nodes (e.g., SN2, CP node 5, UP node 6). The network interface 2803 may include, for example, a network interface card (NIC) compliant with IEEE 802.3 series.

The processor 2804 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. Processor 2804 may include multiple processors. For example, the processor 2804 may be a modem processor (eg, Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (eg, Central Processing Unit (CPU)) or Micro Processing Unit (CPU) that performs control plane processing. MPU)) may be included.

The memory 2805 is composed of a combination of a volatile memory and a non-volatile memory. The volatile memory is, for example, Static Random Access Memory (SRAM) or Dynamic RAM (DRAM), or a combination thereof. The non-volatile memory is a mask Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, hard disk drive, or any combination thereof. Memory 2805 may include storage located off processor 2804. In this case, the processor 2804 may access the memory 2805 via the network interface 2803 or an I/O interface (not shown).

The memory 2805 may store one or more software modules (computer programs) 2806 including a command group and data for performing processing by the MN 1 described in the above-described embodiments. In some implementations, the processor 2804 may be configured to perform the processing of the MN1 described in the above embodiments by reading the software module 2806 from the memory 2805 and executing it.

FIG. 29 is a block diagram showing a configuration example of the UE 3. Radio Frequency (RF) transceiver 2901 performs analog RF signal processing in order to communicate with MN1 and SN2. The RF transceiver 2901 may include multiple transceivers. The analog RF signal processing performed by the RF transceiver 2901 includes frequency up conversion, frequency down conversion, and amplification. The RF transceiver 2901 is coupled with the antenna array 2902 and the baseband processor 2903. The RF transceiver 2901 receives modulated symbol data (or OFDM symbol data) from the baseband processor 2903, generates a transmission RF signal, and supplies the transmission RF signal to the antenna array 2902. Further, the RF transceiver 2901 generates a baseband reception signal based on the reception RF signal received by the antenna array 2902, and supplies this to the baseband processor 2903.

The baseband processor 2903 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. Digital baseband signal processing includes (a) data compression/decompression, (b) data segmentation/concatenation, (c) transmission format (transmission frame) generation/decomposition, and (d) transmission channel coding/decoding. , (E) modulation (symbol mapping)/demodulation, and (f) generation of OFDM symbol data (baseband OFDM signal) by Inverse Fast Fourier Transform (IFFT). On the other hand, the control plane processing includes layer 1 (eg, transmission power control), layer 2 (eg, radio resource management, and hybrid automatic repeat request (HARQ) processing), and layer 3 (eg, attach, mobility, and call management). Signaling management).

For example, the digital baseband signal processing by the baseband processor 2903 may include signal processing of Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, MAC layer, and PHY layer. Further, the control plane processing by the baseband processor 2903 may include processing of Non-Access Stratum (NAS) protocol, RRC protocol, and MAC CE.

The baseband processor 2903 may include a modem processor (e.g., DSP) that performs digital baseband signal processing and a protocol stack processor (e.g., CPU or MPU) that performs control plane processing. In this case, the protocol stack processor that performs the control plane process may be shared with the application processor 2904 described later.

The application processor 2904 is also called a CPU, MPU, microprocessor, or processor core. The application processor 2904 may include a plurality of processors (a plurality of processor cores). The application processor 2904 is a system software program (Operating System (OS)) read from the memory 2906 or a memory (not shown) and various application programs (eg, call application, WEB browser, mailer, camera operation application, music playback). Various functions of the UE 3 are realized by executing the (application).

In some implementations, the baseband processor 2903 and application processor 2904 may be integrated on a single chip, as shown by the dashed line (2905) in FIG. In other words, the baseband processor 2903 and the application processor 2904 may be implemented as one System on Chip (SoC) device 2905. SoC devices are also sometimes referred to as system large scale integration (LSI) or chipsets.

The memory 2906 is a volatile memory or a non-volatile memory or a combination thereof. Memory 2906 may include multiple physically independent memory devices. Volatile memory is, for example, SRAM or DRAM or a combination thereof. The non-volatile memory is MROM, EEPROM, flash memory, or hard disk drive, or any combination thereof. For example, memory 2906 may include an external memory device accessible by baseband processor 2903, application processor 2904, and SoC 2905. Memory 2906 may include embedded memory devices integrated within baseband processor 2903, application processor 2904, or SoC 2905. Further, the memory 2906 may include a memory in a Universal Integrated Circuit Card (UICC).

The memory 2906 may store one or more software modules (computer programs) 2907 including a command group and data for performing processing by the UE 3 described in the above-described embodiments. In some implementations, the baseband processor 2903 or the application processor 2904 is configured to read the software module 2907 from the memory 2906 and execute it to perform the processing of the UE3 described in the above embodiments with reference to the drawings. May be done.

FIG. 30 is a block diagram showing a configuration example of the AMF/SMF entity 5 according to the above embodiment. Referring to FIG. 30, the AMF/SMF entity 5 includes a network interface 3001, a processor 3002, and a memory 3003. The network interface 3001 is used to communicate with network nodes (e.g., RAN nodes, other core network nodes). The network interface 3001 may include, for example, a network interface card (NIC) compliant with IEEE 802.3 series.

The processor 3002 may be, for example, a microprocessor, MPU, or CPU. Processor 3002 may include multiple processors.

The memory 3003 is composed of a combination of a volatile memory and a non-volatile memory. Volatile memory is, for example, SRAM or DRAM or a combination thereof. The non-volatile memory is, for example, an MROM, a PROM, a flash memory, a hard disk drive, or a combination thereof. Memory 3003 may include storage located remotely from processor 3002. In this case, the processor 3002 may access the memory 3003 via the network interface 3001 or an I/O interface (not shown).

The memory 3003 may store one or a plurality of software modules (computer programs) 3004 including an instruction group and data for performing processing by the AMF/SMF entity 5 described in the above-described embodiments. In some implementations, the processor 3002 is configured to perform the processing of the AMF/SMF entity 5 described in the above embodiments by reading and executing the one or more software modules 3004 from the memory 3003. Good.

As described with reference to FIGS. 28, 29, and 30, each of the processors included in the MN1, SN2, UE3, and AMF/SMF entity 5 according to the above-described embodiment has the algorithm described with reference to the drawings. One or a plurality of programs including a group of instructions for causing a computer to execute This program can be stored using various types of non-transitory computer readable media, and can be supplied to a computer. Non-transitory computer readable media include various types of tangible storage media. Examples of non-transitory computer readable media are magnetic recording media (eg flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (eg magneto-optical disks), Compact Disc Read Only Memory (CD-ROM), CD- R, CD-R/W, semiconductor memory (for example, mask ROM, Programmable ROM (PROM), Erasable PROM (EPROM), flash ROM, Random Access Memory (RAM)) are included. In addition, the program may be supplied to the computer by various types of transitory computer readable media. Examples of transitory computer-readable media include electrical signals, optical signals, and electromagnetic waves. The transitory computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

<Other embodiments>
The above embodiments have been described primarily with respect to the NR-NR DC example. The configuration and operation of the device shown in these embodiments can be used for MR-DC with the 5GC.

The above embodiment has provided the example in which the information elements (e.g., SCG-Config) and the messages transmitted between the MN1 and the SN2 have names and configurations assuming LTE DC. However, the names and structures of the information elements and messages of NR-NR DC do not have to be the same as those of LTE DC. For example, at least some of the information elements included in SCG-Config may be defined as the information elements of the Xn interface between MN1 and SN2. Furthermore, the name and structure of the information element may be different depending on the form of DC (e.g., NR-NR DC, MR-DC with the 5GC (e.g., NG-EN-DC, NE-DC)). For example, in NR-NR DC, both MN and SN use NR RRC protocol, but in MR-DC, MN and SN use different RRC protocols (that is, LTE RRC protocol and NR RRC protocol). Therefore, in MR-DC, it may be sufficient for the MN and SN to know the combination of the PDU session identifier, the included QoS flow, and the DRB identifier.

The above embodiments have been described with respect to the Dual Connectivity example. However, it may be applied in Multi Connectivity (MC). For example, in the above-described embodiment, when two SNs (eg, SN2-1 and SN2-2) exist for one MN in communication with one UE, three N3 tunnels (NG-U tunnels) are used. ) May be applied to configurations that are simultaneously supported for one PDU session. In other words, one PDU session may be split into MN1, SN2-1, and SN2-2. Alternatively, one PDU session may be split into two SN2-1 and SN2-2, or MN1 and one of the two SNs (SN2-1 or SN2-2). May be. Thus, in the above-described embodiment, in the MC, one PDU session is split into three or more RAN nodes (ie, MN and SNs) (that is, three or more N3 tunnels corresponding to one PDU session). (NG-U tunnel) is configured).

The above-described embodiment is premised on that the UE 3 supporting the NR-NR DC or MR-DC function supports the PDU session split function. However, there may be a UE that supports the NR-NR DC or MR-DC function but does not support the PDU session split function. For example, a terminal capability (e.g., PDU session split support, PDU-SessionTypeSplit) indicating the (functional) support of PDU session split may be defined.

The terminal capability indicating the support of PDU session split may be UE AS layer capability (UE AS Capability, eg UE radio access capability) or UE NAS layer capability (UE NAS Capability, eg UE network capability). May be When the terminal capability is the capability of the UE AS layer, the UE3 may send an information element indicating the terminal capability to the MN1 in an RRC message. On the other hand, when the terminal capability is UE NAS layer capability, the UE 3 may send an information element indicating the terminal capability to the AMF/SMF entity 5 by a NAS message.

Alternatively, when the terminal capability is the UE NAS layer capability, the AMF/SMF entity 5 may notify the MN 1 of the terminal capability. The notification of the terminal capability from the AMF/SMF entity 5 to the MN 1 may be performed for each UE.

Alternatively, the AMF/SMF entity 5 considers whether the UE3 has the terminal capability to determine whether the PDU session split is allowed for the PDU session for the UE3. May be. For example, the AMF/SMF entity 5 may receive the information element indicating the terminal capability from the UE 3 or the subscriber information server (e.g., Home Subscriber Server (HSS)) in the PDU session establishment procedure. Then, the AMF/SMF entity 5 may determine whether or not the PDU session split is permitted for the PDU session for the UE 3 in consideration of the received information element. In other words, the AMF/SMF entity 5 may determine, on a UE basis, whether to allow PDU session split based on the terminal capability of each UE.

Thereby, the MN1 or the AMF/SMF entity 5 appropriately determines one or more RAN nodes to which the PDU session for the UE3 is established (mapped) in consideration of the PDU session split capability of the UE3. can do. Alternatively, the AMF/SMF AMF/SMF entity 5 can appropriately determine whether to permit the PDU session split request from the MN 1.

The MN1 and SN2 described in the above embodiments may be implemented based on the Cloud Radio Access Network (C-RAN) concept. C-RAN is sometimes called Centralized RAN. Therefore, the processes and operations performed by each of the MN1 and SN2 described in the above embodiments are provided by the Digital Unit (DU) included in the C-RAN architecture or by the combination of DU and Radio Unit (RU). May be. DU is called Baseband Unit (BBU) or Central Unit (CU). RU is also called Remote Radio Head (RRH), Remote Radio Equipment (RRE), Distributed Unit (DU), or Transmission and Reception Point (TRP). That is, the processes and operations performed by each of the MN1 and SN2 described in the above embodiments may be provided by any one or a plurality of wireless stations (or RAN nodes).

Further, the above-described embodiment is merely an example regarding application of the technical idea obtained by the present inventor. That is, the technical idea is not limited to the above-described embodiment, and it goes without saying that various modifications can be made.

This application claims the priority on the basis of Japanese application Japanese Patent Application No. 2017-154365 for which it applied on August 9, 2017, and takes in those the indications of all here.

1 Master node (MN)
2 Secondary node (SN)
3 User Equipment (UE)
4 Core network 5 Control plane (CP) node 6 User plane (UP) node 7 RAN node 8 Target gNB
2801 RF transceiver 2804 processor 2805 memory 2901 RF transceiver 2903 baseband processor 2904 application processor 2906 memory 3002 processor 3003 memory

Claims (42)

A master radio access network (RAN) node,
Memory and
At least one processor coupled to said memory;
Equipped with
The at least one processor is configured to send a request for modification of a first PDU session already established between the wireless terminal and a user plane function in the core network to a control plane function in the core network,
The modification request implicitly or explicitly indicates that a PDU session split is required for the already established first PDU session,
The modification request is for the user plane function and the master RAN node to specify one or more specific QoS flows among a plurality of Quality of Service (QoS) flows associated with the already established first PDU session. Causing the control plane function to control the user plane function to move from a first tunnel between the user plane function and a second tunnel between the user plane function and a secondary RAN node,
Master RAN node. The at least one processor determines whether the PDU session split is allowed for the first PDU session in the procedure of establishing the first PDU session prior to sending the modification request. Configured to receive a first indication on a per-PDU session basis or on a per QoS flow basis indicating from the control plane function,
The master RAN node according to claim 1. The first indication is included in a message sent from the control plane function to the master RAN node to request setup of PDU session resources for the first PDU session,
The master RAN node according to claim 2. The at least one processor permits the PDU session split in a procedure of setting up or modifying a signaling connection between the master RAN node and the control plane function, which is performed prior to transmission of the modification request. Configured to receive a second indication from the control plane function indicating whether or not
The master RAN node according to claim 1. The second display shows permission or disapproval of the PDU session split for each network slice,
The master RAN node according to claim 4. The at least one processor is configured to receive, prior to sending the modification request, a third indication per wireless terminal indicating whether the PDU session split is allowed from the control plane function. ing,
The master RAN node according to claim 1. The modification request includes PDU session type information that explicitly indicates the need for the PDU session split.
The master RAN node according to any one of claims 1 to 6. The modification request includes an identifier for each of the one or more QoS flows to implicitly or explicitly indicate that the PDU session split is required for the first PDU session,
The master RAN node according to any one of claims 1 to 7. The at least one processor is configured to request an allocation of resources for dual connectivity for the wireless terminal and send an inter-node message to the secondary RAN node that implicitly or explicitly indicates the PDU session split. The
The master RAN node according to any one of claims 1 to 8. The inter-node message includes PDU session establishment type information that explicitly indicates that the PDU session split is applied to the first PDU session or the one or more QoS flows,
The master RAN node according to claim 9. The at least one processor is configured to request to perform secondary cell group configuration for dual connectivity and to send to the wireless terminal an RRC connection reconfiguration message implicitly or explicitly indicating the PDU session split. Will be
The master RAN node according to any one of claims 1 to 10. The secondary cell group configuration includes an identifier of the first PDU session and one or more data associated with the one or more QoS flows to implicitly or explicitly indicate the PDU session split. And a radio bearer identifier,
The master RAN node according to claim 11. The secondary cell group configuration includes data radio bearer type information that explicitly indicates that the PDU session split is applied to the first PDU session or the one or more QoS flows,
The master RAN node according to claim 11 or 12. The at least one processor is configured to send a handover request message to the target RAN node to request a handover of the wireless terminal from the master RAN node to a target RAN node,
The handover request message indicates that the PDU session split is applied to the first PDU session or the one or more QoS flows,
The master RAN node according to any one of claims 1 to 13. The handover request message includes PDU session type information or QoS flow type information that explicitly indicates that the PDU session split is applied to the first PDU session or the one or more QoS flows. ,
The master RAN node according to claim 14. The handover request message includes terminal context reference information for distinguishing the wireless terminal in the secondary RAN node,
The terminal context reference information includes an indication that the PDU session split is applied to the first PDU session or the one or more QoS flows,
The master RAN node according to claim 15. A control plane node located in the core network,
Memory and
At least one processor coupled to said memory;
Equipped with
The at least one processor is configured to receive from a master radio access network (RAN) node a modification request for a first PDU session already established between a wireless terminal and a user plane function in the core network,
The modification request implicitly or explicitly indicates that a PDU session split is required for the already established first PDU session,
The at least one processor is further responsive to receipt of the modification request to identify one or more of a plurality of Quality of Service (QoS) flows associated with the already established first PDU session. Controlling the user plane function to move a QoS flow of the same from a first tunnel between the user plane function and the master RAN node to a second tunnel between the user plane function and a secondary RAN node. Composed,
Control plane node. The at least one processor determines whether the PDU session split is allowed for the first PDU session in the procedure of establishing the first PDU session prior to sending the modification request. Configured to send a first indication on a per-PDU session basis or on a per QoS flow basis to the master RAN node,
The control plane node according to claim 17. The at least one processor is configured to include the first indication in a message sent to the master RAN node to request setup of PDU session resources for the first PDU session,
The control plane node according to claim 18. In the procedure of setting up or modifying a signaling connection between the master RAN node and the control plane node, which is performed before the transmission of the modification request, the at least one processor is configured so that the PDU session split is performed. Configured to send a second indication to the master RAN node indicating whether to be authorized,
A control plane node according to any one of claims 17-19. The second display shows permission or disapproval of the PDU session split for each network slice,
The control plane node according to claim 20. The at least one processor is configured to send a wireless terminal-based third indication to the master RAN node indicating whether the PDU session split is allowed prior to sending the modification request. Is
A control plane node according to any one of claims 17 to 21. The at least one processor is configured to control the user plane function to move the one or more QoS flows to the second tunnel in response to receiving the modification request.
The control plane node according to any one of claims 17 to 22. The modification request includes PDU session type information that explicitly indicates the need for the PDU session split.
A control plane node according to any one of claims 17 to 23. The at least one processor splits the first PDU session into two or more RAN nodes if the PDU session type information indicates that the PDU session split is required or required. Configured to recognize that you need to,
The control plane node according to claim 24. The at least one processor moves the first PDU session to another RAN node if the PDU session type information does not indicate that the PDU session split is needed or required. Configured to recognize that you need to,
The control plane node according to claim 25. The modification request includes an identifier for each of the one or more QoS flows to implicitly or explicitly indicate that the PDU session split is required for the first PDU session,
A control plane node according to any one of claims 17 to 26. The modification request includes a downlink Transport Network Layer (TNL) address for the first PDU session,
The at least one processor may determine whether the downlink TNL address is a new downlink address or additional downlink addresses depending on whether the modification request indicates that the PDU session split is required. Configured to determine if it is a link address,
A control plane node according to any one of claims 17 to 27. A secondary radio access network (RAN) node,
Memory and
At least one processor coupled to said memory;
Equipped with
The at least one processor is configured to receive an inter-node message requesting allocation of resources for dual connectivity for a wireless terminal from a master RAN node,
The inter-node message further implicitly or explicitly indicates that the PDU session split is applied to the already established first PDU session between the wireless terminal and the user plane function in the core network. ,
In the PDU session split, one or more first QoS flows of a plurality of Quality of Service (QoS) flows associated with the first PDU session are defined by the user plane function and the master RAN node. Via a first tunnel between the one or more second QoS flows of the plurality of QoS flows and a second tunnel between the user plane function and the secondary RAN node. Including the configuration to be transferred,
Secondary RAN node. The inter-node message includes PDU session establishment type information that explicitly indicates that the PDU session split applies to the first PDU session or the one or more second QoS flows,
The secondary RAN node according to claim 29. The at least one processor is further configured to send an RRC connection reconfiguration message indicating a secondary cell group configuration for the dual connectivity to the wireless terminal,
The RRC connection reconfiguration message further implicitly or explicitly indicates that the PDU session split is applied to the first PDU session,
The secondary RAN node according to claim 29 or 30. A wireless terminal,
Memory and
At least one processor coupled to said memory;
Equipped with
The at least one processor is configured to receive an RRC connection reconfiguration message indicating a secondary cell group configuration for dual connectivity from a master (RAN) node or a secondary RAN node,
The RRC connection reconfiguration message further implicitly or explicitly indicates that PDU session split is applied to the already established first PDU session between the wireless terminal and a user plane function in the core network. Shown in
In the PDU session split, one or more first QoS flows of a plurality of Quality of Service (QoS) flows associated with the first PDU session are defined by the user plane function and the master RAN node. And a second QoS flow of one or more of the plurality of QoS flows is transferred via a second tunnel between the user plane function and a secondary RAN node. Including the configuration,
Wireless terminal. The secondary cell group configuration includes an identifier of the first PDU session and one or more data associated with the one or more QoS flows to implicitly or explicitly indicate the PDU session split. And a radio bearer identifier,
The wireless terminal according to claim 32. The secondary cell group configuration includes type information that explicitly indicates that the PDU session split is applied to the first PDU session or the one or more QoS flows,
The wireless terminal according to claim 32 or 33. A method in a master radio access network (RAN) node, comprising:
Comprising sending a request to modify a first PDU session already established between the wireless terminal and a user plane function in the core network to a control plane function in the core network,
The modification request implicitly or explicitly indicates that a PDU session split is required for the already established first PDU session,
The modification request is for the user plane function and the master RAN node to specify one or more specific QoS flows among a plurality of Quality of Service (QoS) flows associated with the already established first PDU session. Causing the control plane function to control the user plane function to move from a first tunnel between the user plane function and a second tunnel between the user plane function and a secondary RAN node,
Method. A method in a control plane node located in a core network,
Receiving from a master radio access network (RAN) node a modification request for a first PDU session already established between a wireless terminal and a user plane function in the core network, wherein the modification request is Implicitly or explicitly indicating that a PDU session split is required for the established first PDU session; and
A specific one or more QoS flows of a plurality of Quality of Service (QoS) flows associated with the already established first PDU session are assigned to a first one between the user plane function and the master RAN node. Controlling the user plane function to move from the second tunnel between the user plane function and the secondary RAN node;
Comprising a method. A method in a secondary radio access network (RAN) node, comprising:
Comprising receiving from a master RAN node an internode message requesting to allocate resources for dual connectivity for wireless terminals,
The inter-node message further implicitly or explicitly indicates that the PDU session split is applied to the already established first PDU session between the wireless terminal and the user plane function in the core network. ,
In the PDU session split, one or more first QoS flows of a plurality of Quality of Service (QoS) flows associated with the first PDU session are defined by the user plane function and the master RAN node. Via a first tunnel between the one or more second QoS flows of the plurality of QoS flows and a second tunnel between the user plane function and the secondary RAN node. Including the configuration to be transferred,
Method. A method in a wireless terminal, comprising:
Comprising receiving an RRC connection reconfiguration message indicating a secondary cell group configuration for dual connectivity from a master (RAN) node or a secondary RAN node,
The RRC connection reconfiguration message further implicitly or explicitly indicates that PDU session split is applied to the already established first PDU session between the wireless terminal and a user plane function in the core network. Shown in
In the PDU session split, one or more first QoS flows of a plurality of Quality of Service (QoS) flows associated with the first PDU session are defined by the user plane function and the master RAN node. And a second QoS flow of one or more of the plurality of QoS flows is transferred via a second tunnel between the user plane function and a secondary RAN node. Including the configuration,
Method. A non-transitory computer readable medium storing a program for causing a computer to perform a method in a master radio access network (RAN) node,
The method comprises sending a modification request for a first PDU session already established between a wireless terminal and a user plane function in the core network to a control plane function in the core network,
The modification request implicitly or explicitly indicates that a PDU session split is required for the already established first PDU session,
The modification request is for the user plane function and the master RAN node to specify one or more specific QoS flows among a plurality of Quality of Service (QoS) flows associated with the already established first PDU session. Causing the control plane function to control the user plane function to move from a first tunnel between the user plane function and a second tunnel between the user plane function and a secondary RAN node,
Non-transitory computer-readable medium. A non-transitory computer-readable medium storing a program for causing a computer to perform a method in a control plane node arranged in a core network,
The method is
Receiving from a master radio access network (RAN) node a modification request for a first PDU session already established between a wireless terminal and a user plane function in the core network, wherein the modification request is Implicitly or explicitly indicating that a PDU session split is required for the established first PDU session; and a plurality of Quality of Service (QoS) associated with the already established first PDU session. ) Moving one or more specific QoS flows of the flows from a first tunnel between the user plane function and the master RAN node to a second tunnel between the user plane function and a secondary RAN node Controlling the user plane function as follows;
A non-transitory computer-readable medium comprising. A non-transitory computer-readable medium storing a program for causing a computer to perform a method in a secondary radio access network (RAN) node, comprising:
The method comprises receiving an internode message requesting to allocate resources for dual connectivity for a wireless terminal from a master RAN node,
The inter-node message further implicitly or explicitly indicates that the PDU session split is applied to the already established first PDU session between the wireless terminal and the user plane function in the core network. ,
In the PDU session split, one or more first QoS flows of a plurality of Quality of Service (QoS) flows associated with the first PDU session are defined by the user plane function and the master RAN node. Via a first tunnel between the one or more second QoS flows of the plurality of QoS flows and a second tunnel between the user plane function and the secondary RAN node. Including the configuration to be transferred,
Non-transitory computer-readable medium. A non-transitory computer-readable medium storing a program for causing a computer to perform the method in a wireless terminal,
The method comprises receiving an RRC connection reconfiguration message indicating a secondary cell group configuration for dual connectivity from a master (RAN) node or a secondary RAN node,
The RRC connection reconfiguration message further implicitly or explicitly indicates that PDU session split is applied to the already established first PDU session between the wireless terminal and a user plane function in the core network. Shown in
In the PDU session split, one or more first QoS flows of a plurality of Quality of Service (QoS) flows associated with the first PDU session are defined by the user plane function and the master RAN node. And a second QoS flow of one or more of the plurality of QoS flows is transferred via a second tunnel between the user plane function and a secondary RAN node. Including the configuration,
Non-transitory computer-readable medium.

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